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HIV care engagement was likely a cause of quicker COVID-19 vaccination uptake in people who inject drugs who also had HIV and had achieved viral suppression, according to a study published in Preventive Medicine Reports. Vaccine uptake could be further helped with targeted improvements in HIV care, the authors noted.
The vaccines against COVID-19 have been proven safe and effective for people living with HIV (PWH), a population that benefits from the vaccine due to their vulnerability. HIV has previously been associated with higher risks of COVID-19 infection, severe outcomes, and risk of death. Using injection drugs is associated with an increased number of comorbidities, contributing to these individuals higher odds of mortality and intensive care unit (ICU) admission for COVID-19 when using opioids. This study aimed to find differences in vaccine uptake for COVID-19 by HIV status and viral load in people who use injectable drugs.
The researchers used the ALIVE Study to gather a population for this study. Participants who were alive as of April 6, 2021, were included. The ALIVE study collected data on adults 18 years and older who lived in or near Baltimore, Maryland, and who had a history of using injection drugs. Characteristics, substance use behaviors, and health status were all collected biannually from participants. Viral load was assessed through blood samples. Vaccination status data for COVID-19 were collected from the Chesapeake Regional Information Systems for our Patients health information exchange, which collects data from throughout the region. Sociodemographic, substance use, and health status self-reported data were also included.
Healthcare cure concept with a hand in blue medical gloves holding Coronavirus, Covid 19 virus, vaccine vial | Image credit: Leigh Prather - stock.adobe.com
There were 960 participants included in the study, with most participants identifying as Black (78%) and male (67%); 74% were 50 years or older. In this overall sample, 70% were vaccinated with at least 1 dose of the COVID019 vaccine. Among the 317 PWH (28%), 85% had a viral load of less than 400 copies/L.
Median time to completion of the primary series of the vaccine was 24.3 weeks (95% CI, 19.9-28.9). The median time to vaccination was faster in PWH who were virally suppressed (12.4 weeks; 95% CI, 9.4-18.4) compared with participants who did not have HIV (28.3 weeks; 95% CI, 23.9-40.4). However, PWH with detectable viral loads were slower to vaccination (median time undefined because <50% completed the primary series). The primary series was completed fastest in those 65 years and older (8.1 weeks; 95% CI, 5.0-20.9) compared with those younger than 50 years (undefined) or aged 50 to 64 years (15.6 weeks; 95% CI, 13.1-20.6); participants were also faster to get vaccinated if they were Black, were male, or had a previous chronic lung disease. Participants who had a lower income or were homeless were slower to the uptake of the vaccine.
Participants who reported recent injection drug use were slow to completion of the primary series. Participants who reported noninjection stimulant use and were smoking 1 pack or more a day of cigarettes also reported slower completion of primary series.
In unadjusted models, participants who were virally suppressed PWH had a higher likelihood of completing the COVID-19 vaccine series than those without HIV (HR, 1.43; 95% CI, 1.18-1.73). In an adjusted model, PWH who had an undetectable viral load were also more likely to complete their primary series (adjusted HR, 1.23; 95% CI, 1.07-1.50). PWH who had higher viral loads were found to be less likely to complete the primary series (adjusted HR, 0.72; 95% CI, 0.45-1.16) than those without HIV, although this result was not statistically significant.
There were some limitations to this study. Using the start date of phase 3 general eligibility for the vaccine rather than the first day of phase 1A select eligibility could have excluded participants who were vaccinated prior to the index date. There were not enough data on employment to draw any conclusions on its association with vaccine eligibility. This study could not account for changes in variables occurring during follow-up.
The researchers found that there was a significant relationship between HIV viral suppression in people using injectable drugs and increasing uptake of the COVID-19 vaccine.
While additional research is warranted in the context of HIV, injection drug use, and COVID-19 prevention, our findings support interventions targeting both sociostructural barriers to care as well as interventions to improve the HIV care continuum for the added value of health care engagement and COVID-19 vaccine uptake, the authors concluded.
Research
Baker P, Cepeda JA, Schluth C, et al. Time-to-completion of COVID-19 vaccination primary series varies by viral load status among people who inject drugs in Baltimore, Maryland. Prev Med Rep. Published online September 28, 2023. doi:10.1016/j.pmedr.2023.102448
The US Department of Health and Human Services (HHS) today announced more than $500 million more in funding through its Project NextGen program to speed the development of new vaccines and treatments for COVID-19. The funding, through the Administration for Strategic Planning and Response (ASPR), includes three next-generation vaccines and allows the developers to more quickly start phase 2 clinical trials.
Dawn OConnell, JD, assistant secretary for preparedness and response at HHS, said in a statement, "The vaccine selections and funding announced today are important steps forward for Project NextGenwith vaccine and therapeutics candidates moving quickly to clinical trials that will start in the coming months."
First announced in April, Project NextGen is a $5 billion federal effort to speed the development of new COVID vaccines and treatments. Todays announcement comes on top of $1.4 billion in countermeasure awards announced in August.
HHS said the three vaccine candidates are distinct from each other and target stronger, broader, or longer-lasting immune responses.
Scientists and public health experts have been pushing for better COVID vaccines, including ones that provide broader protection against a range of coronaviruses and ones that can cut transmission and symptoms. Early this year, a group led by the Center for Infectious Disease Research and Policy, which publishes CIDRAP News, published aroadmapfor advancing better vaccines against coronaviruses.
HHS said intranasal vaccines have the potential to stop viruses at the infection site, and vaccines containing self-amplifying mRNA (samRNA) and additional antigens may prompt a stronger immune response than current vaccines.
By investing in next-generation vaccines and treatments, we can improve our ability to respond to new variants, reduce transmission, stop infections, and save lives.
One of the candidate vaccines is a live-attenuated intranasal vaccine from Codagenix, which announced initial phase 1 clinical trial findings earlier this week. Another is a vector-based intranasal vaccine from CastleVax, a research and development arm of Mount Sinai Health Systems, which announced promising initial phase 1 findings for its vaccine in July.
The third candidate vaccine is a samRNA vaccine from Gritstone Bio, which is slated to detail promising results from three ongoing phase 1 clinical trials this week at the ID Week meeting in Boston. In a press release this week, Andrew Allen, MD, PhD, the companys chief executive officer, said, "These data reaffirm previous findings that our samRNA vaccines have the potential to drive highly durable antibody responses, to enhance immunity through broader T cell responses, and to accomplish this at RNA doses as low as 3 micrograms, one tenth the dose of currently approved mRNA vaccines for COVID-19."
HHS also announced $240 million in funding to four companies to support vaccine clinical studies and to improve sampling, from cold-chain management to increasing central lab capacity.
It also awarded about $241 million to six companies to boost preparedness for future COVID outbreaks and to improve access to treatment, such as shortening the development timeline for mRNA-expressed monoclonal antibodies and advancing the development of vaccine patches.
HHS Secretary Xavier Becerra, JD, said the investments signal the Biden-Harris administrations commitment to keeping people safe from COVID. "By investing in next-generation vaccines and treatments, we can improve our ability to respond to new variants, reduce transmission, stop infections, and save lives. Through Project NextGen, we are combining research and development expertise at HHS with the lessons learned throughout the pandemic to protect our nation from COVID-19."
A new mouse model of infection with the COVID-19-causing SARS-CoV-2 virus during pregnancy tracks closely the disease course doctors have observed in SARS-CoV-2-infected pregnant patients, and suggests that treatment with the antiviral Paxlovid provides protection for both mother and child. The new model is described in a study led by researchers at the Johns Hopkins Bloomberg School of Public Health.
The researchers found that pregnant mice infected with SARS-CoV-2 later in gestation tended to have worse COVID-19-like disease, as seen in pregnant patients with SARS-CoV-2 infections. Treating the mice with the active ingredients in Paxlovidan oral antiviral drug approved by the Food and Drug Administration for use against SARS-CoV-2 infection, but not widely used in pregnant patients with COVID-19reduced their viral loads and disease signs in mothers, and prevented growth and developmental deficits in their offspring.
The study appears online in the Journal of Clinical Investigation.
Our findings are consistent with the overall public health message that Paxlovid is safe and effective, and that if youre pregnant it can protect you and your baby, says study co-senior author Sabra Klein, PhD, professor in the Department of Molecular Microbiology and Immunology at the Bloomberg School.
The COVID-19 pandemic is a reminder that pregnant people are an at-risk population for more severe viral diseasesso much so that they are often among priority groups that receive immediate access to new antiviral treatments when they are authorized or approved by the FDA. During the pandemic, doctors observed that SARS-CoV-2 infection during pregnancyespecially late pregnancytends to cause more severe COVID-19, with a threefold greater risk of intensive care admission than the general population, as well as increased risks of preterm birth and neurodevelopmental disorders in affected infants.
Research shows that late pregnancy normally features a suppression of some maternal immune pathways, presumably to help protect the unborn child from maternal immune attack. But just how this leads to worsened viral illness in pregnant mothers and developmental deficits in children has been unclear.
To better understand these mechanisms, Klein and colleagues developed a model of SARS-CoV-2 infection in pregnancy using a standard outbred strain of laboratory micewhich means that like humans, the offspring are not identical to the mother. They exposed three sets of the animals, at three different stages of pregnancy, to a version of SARS-CoV-2 adapted to grow well in mice. The infection stages corresponded roughly to the first, second, and third trimesters of human pregnancy.
The researchers found that the pregnant mice infected in the equivalent of the third trimester had significantly worse disease symptoms, on average, compared to the other pregnant or non-pregnant mice. These symptoms included weight loss, higher levels of virus in the lungs, and evidence of lung damage, and were associated with reduced antiviral immunity.
The offspring of the third trimester-infected mothers also fared worse than the others, with slower brain development and less overall growth. Although the researchers found no sign of direct viral infection in the placentas of the mouse offspring, there was evidence of placental cell loss. The researchers are still investigating how a respiratory virus causes this placental damage, but they suspect that it may work via a disruption of normal levels of the hormone progesterone, which has important roles in establishing the placenta and maintaining pregnancy.
Finally, the researchers tested the ability of Paxlovid to protect pregnant mice from illness following SARS-CoV-2 infection. Paxlovid is a mix of an anti-SARS-CoV-2 drug called nirmatrelvir and an anti-HIV drug called ritonavirthe latter boosts the activity of nirmatrelvir by inhibiting an enzyme that would otherwise quickly break it down.
Mouse-equivalent doses of these two drugs, administered four hours after infection, greatly reduced disease symptoms in mice infected late in pregnancy, and prevented adverse growth and developmental effects on their offspring, says Patrick Creisher, one of the studys co-first authors.
He and Jamie Perry, ScM, were graduate students working in the Klein Lab at the time of the study. Creisher is currently a PhD student at the Bloomberg School. Perry is a program specialist at the National Institute of Allergy and Infectious Diseases.
Although Paxlovid is FDA-approved for use in pregnancy-based observational studies, pregnant patients were excluded from clinical trials of the treatment, as they have been for most clinical trials since the 1970s, due to concerns about enhanced risk and liability. While most companies study drug toxicity in pregnant animals, they do not typically test drug efficacy in pregnant animals. This exclusion, says Klein, probably helps explain the lower use of the treatment in pregnancy.
When pregnancy is an exclusion factor in clinical trials, pregnant people inherently question the safety of the drug for them and their babies, she says. All too often when drugs, including antivirals, are approved for use in pregnant patients, the prescription and uptake is low out of an abundance of caution and fear.
Klein adds that she hopes the results in the new mouse model will encourage greater use of Paxlovid to protect against COVID-19 in pregnancyand will discourage pharma companies from always treating pregnancy as an exclusion condition, especially in cases like this, where the drugs are safe.
The other co-senior authors of the study were Andrew Pekosz, PhD, a professor in the Bloomberg Schools Department of Molecular Microbiology and Immunology; and Irina Burd, MD, PhD, Sylvan Frieman, MD Professor and chair of the Department of Obstetrics, Gynecology and Reproductive Sciences at the University of Maryland School of Medicine.
Adverse outcomes in SARS-CoV-2 infected pregnant mice are gestational age-dependent and resolve with antiviral treatment was co-authored by Patrick Creisher, Jamie Perry, Weizhi Zhong, Jun Lei, Kathleen Mulka, Hurley Ryan, Ruifeng Zhou, Elgin Akin, Anguo Liu, Wayne Mitzner, Irina Burd, Andrew Pekosz, and Sabra Klein.
Support for the research was provided by the National Institutes of Health (R01HD097608, T32AI007417-26, N7593021C00045).
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Media contacts: Barbara Benham at bbenham1@jhu.edu and Kathy Marmon at kmarmon@jhu.edu.
Doctors in the Lehigh Valley say theyre seeing normal seasonal demand for the flu vaccine, but hesitancy around the COVID-19 vaccine may be keeping some from getting the updated shots.
Lehigh Valley Health Network has free walk-in and drive-in flu vaccine clinicsscheduled throughout October and early November. St. Lukes University Health Network also has the flu vaccine available at pediatric, family doctor and primary care offices.
This years flu vaccine appears to be a good match for the dominant strains of flu that have been circulating its about 52% effective at reducing hospitalizations, data shows and there is ample supply available in the Lehigh Valley.
Dr. Jeffry Jahre, senior vice president of medical and academic affairs and chief emeritus of infectious diseases for St. Lukes, said everyone eligible to receive the flu vaccine should take it. And so far, uptake has been good among St. Lukes employees and patients, he said.
Requests for flu vaccine this year are good, theyre not any less than what they have been in the past, Jahre said. As a whole, we have found the compliance, the uptake of influenza vaccines is actually on par with what we have seen in the past.
Dr. Alex Benjamin, LVHNs chief infection control and prevention officer, said that so far, volumes of people getting the flu vaccines at their clinics are the same as this time last year, about 10,000. But he said LVHN only began offering the flu shot at clinics and practices last week, and with its annual drive-thru clinic at Dorney Park several weeks away, he said they could double those numbers.
LVHN spokesperson Brian Downs added that some patients defer their flu shot to later this month or November so that can have optimal protection during months that are usually the peak times for flu circulation. By early December, LVHN will have a will know more on public interest in the vaccine and about the significance of flu, Downs said.
Though flu vaccines have been available since early August and in some locations since July, the Centers for Disease Control and Prevention do not have much data available yet on flu vaccine uptake. A recent survey conducted among roughly 20,000 U.S. adults found that about 14% had received their flu vaccine.
The severity of this flu season is also up in the air; the Pennsylvania Department of Health is not yet sharing data for this flu season on its website.
Jahre said flu definitely already is in the Lehigh Valley, albeit limited to a small number of cases, about 10 to 15 per week.
Are we seeing influenza already? The answer of course to that is yes. It hasnt certainly peaked in any way, shape or form, Jahre said.
Australia, which experiences its flu season during the Northern Hemispheres summer, reported a somewhat mild flu season; reported and confirmed cases were moderate and the number of deaths and direct intensive care unit admissions associated with influenza were low.
Benjamin said that is encouraging; also, unlike last year when flu and respiratory syncytial virus, or RSV, already were taking off at this point, that is not the case in the Lehigh Valley and much of the U.S.
Jahre said if previous years are an indication, once people start spending more time inside with lots of other people such as during the holidays, the flu season is likely to pick up, though this isnt set in stone.
New COVID-19 mRNA vaccines also are available, which were approved by the CDC and the U.S. Food and Drug Administration in September. An updated Novavax vaccine also received approval in early October. The mRNA vaccines from Pfizer and Moderna are approved for and recommended for those 6 months and older. The Novavax vaccine is for those 12 and older.
The actual efficacy of the vaccines is currently unknown as the approval of each was contingent on their ability to produce a certain level of antibodies. Jahre said there is every reason to believe the vaccine will perform as expected. Benjamin shared a similar sentiment and said he expects these vaccines will perform comparably to previous vaccines.
Unlike the bivalent booster shots given out last year, the new shots are considered updated vaccines and are based on one strain, in this case the omicron XBB.1.5 variant. As of last week, about 4 million Americans had received the new COVID-19, according to ABC News. About half of adults said they planned on getting the vaccine, according to Kaiser Family Foundations COVID-19 Vaccine Monitor.
Benjamin said that networkwide, LVHN has distributed about 5,000 doses of the new COVID-19 vaccines, primarily the Pfizer version. He said this low number is to be expected since the vaccine has only be available for a few weeks.
I think theres a common pattern: Early adopters are the first ones in line making their appointments and getting their vaccines. Theres also a population who are not going to get vaccinated right away, the vaccine-hesitant. There are probably people who have had COVID in the recent past and dont think they need vaccines right away, Benjamin said.
A St. Lukes spokesperson said the network did not have data available on doses of the new COVID-19 vaccine. Jahre said low uptake and high levels of hesitancy toward getting the COVID-19 vaccine also partially can be attributed to health experts and the government not doing a good job of communicating what the COVID vaccine is capable of doing.
He said that like the flu vaccine, COVID-19 vaccines are best at preventing serious illness, not preventing you from catching the disease.
Weve made it clear to people that if they get influenza and theyve been vaccinated appropriately, the chances of them having the worst consequences of the disease, hospitalization and death, go down enormously, Jahre said. Its not made clear to people that the same situation exists, that you cant rely on the monovalent [COVID-19] vaccine to absolutely prevent disease.
Jahre added that despite the federal government suggesting getting both the flu and COVID-19 vaccines at the same time is fine, he said that might not be the best idea, except from a convenience and potentially cost-saving perspective. He said for older people in particular it may be better to split these vaccinations up as they tend to experience more non-serious side effects.
Jahre added that boys and men ages 12 to 39 may be at higher risk of myocarditis as a complication of the monovalent mRNA vaccines. He said men in this age group who are otherwise healthy and do not live with or have frequent contact with high-risk patients may want to talk with their physician about alternatives such as the Novavax vaccine.
COVID-19 hospitalizations in the Lehigh Valley are low; Jahre said networkwide St. Lukes has been in the low 20s as far as patients hospitalized for COVID. Benjamin said for LVHN, it was in the high 20s until recently but last week those numbers fell to less than 15.
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A recent study published last month in JAMA Network Open adds support for the safety and efficacy of coadministration of COVID-19 and influenza vaccines. This study found that receiving the flu and COVID-19 vaccines simultaneously produced a non-inferior safety and efficacy profile when compared to receiving the COVID-19 vaccine alone.
Getting both vaccines at the same visit is convenient, saving time for patients, caregivers and vaccine providers. But, until now, limited data on the safety and efficacy of coadministration have been published.
Tal Gonen, M.D., and colleagues from the Sheba Medical Center in Israel conducted a study to compare the safety and efficacy of administering both vaccines at the same time. Vaccines were offered to all employees and could be given together or separately. The study included a total of 88 healthcare worker participants between from September 2022 to January 2023. One group received the COVID-19 or flu shot alone, waiting at least 7 days before receiving the other, while the second group received the COVID and flu vaccines on the same day. The participants reported side effects and gave blood samples to reveal titers used for assessing the extent of immune response to the vaccines.
No significant differences in responses were found between the two vaccination schedules, suggesting that coadministration is safe and effective.
These findings are important as the coadministration of vaccines is essential for adherence. This research contributes to the growing body of evidence on the safe coadministration of COVID-19 and flu vaccines, which is particularly relevant for healthcare workers who care for COVID-19 patients and have contact with vulnerable patient populations.
As vaccination efforts continue worldwide, understanding the immunogenicity and reactogenicity of coadministered vaccines is crucial for optimizing public health strategies. Further research is needed to explore the effect of simultaneous administration of booster doses and to assess the coadministration of specific COVID-19 variants with flu vaccines.
Meanwhile, early results from Modernas phase 1/2 study investigating their combination flu-COVID vaccine reflect a strong immune response, according to a press release from the company earlier this month. The trial showed that mRNA-1083, a combination vaccine against influenza and COVID-19, demonstrated strong immunogenicity against both influenza and COVID-19, with an acceptable safety profile.
The phase 1/2 trial compared mRNA-1083 to licensed standalone vaccines, Fluarix and Fluzone HD, and a Spikevax booster. mRNA-1083 achieved antibody titers similar to or greater than the licensed influenza vaccines and achieved SARS-CoV-2 neutralizing antibody titers similar to the Spikevax booster. Reported side effects were similar to the existing COVID-19 boosters; most adverse events were mild or moderate, with less than 4% of trial participants experiencing severe side effects.
Based on these results, Moderna plans to begin a phase 3 trial of mRNA-1083 in adults aged 50 and older. The combination vaccine aims to provide higher compliance, easier administration, and greater convenience for individuals, providers, and healthcare systems. Moderna intends to seek regulatory approval for the combined vaccine in 2025.
From the Jackson-Madison County Regional Health Department:
JACKSON, Tenn. The Jackson-Madison County Regional Health Department will begin giving the updated COVID-19 vaccine onWednesday, October 18. The vaccine will be given daily during normal business hours (8 a.m. 4:30 p.m.).An appointment is required.JMCHD is now taking appointments.
The Center for Disease Control recommends everyone 6 months and older get an updated COVID-19 vaccine to protect against the potentially serious outcomes of COVID-19 illness this fall and winter.
At this time, JMCHD has the Moderna vaccine for all ages.
To receive your COVID-19 vaccine at the Health Department, call 731-423-3020 to make an appointment. JMCHD is no longer accepting walk-ins for COVID-19 vaccination.
FREQUENTLY ASKED QUESTIONS
Can you receive Moderna if you previously had Pfizer?
Yes. Both the CDC and FDA have endorsed mixing COVID shots for older children and adults meaning it is ok to receive a booster from a different manufacturer than the one used for previous doses. This does not apply to children younger than 5 years old, who should still stick with one manufacturer.
Cost
Most patients will receive COVID shots at no additional cost through private insurance or Medicare. Patients will need to bring a health insurance card to their appointment.
For adults without private insurance, the CDCs Bridge Access Program provides no-cost COVID-19 vaccines. JMCHD is a Bridge Access Program location. Children without insurance can receive the vaccines at no cost through the Vaccines For Children program.
Timing
You are eligible for the new vaccine if it has been at least 2 months since your last COVID vaccination.
If you were recently diagnosed with COVID, it is recommended that you wait 3 months after infection before receiving the new vaccine.
Can I get flu and COVID shots at the same time?
Yes. You can get a flu vaccine and COVID vaccine at the same appointment if you are due to receive both.
For additional questions, refer to the JMCHD website (madisoncountytn.gov/144/Health-Department), or call our office at 731-423-3020.
A total of 267,968 cases of hepatitis C were diagnosed between January 2013 and September 2022, resulting in an annual average diagnosis rate of 2.42 per 100,000 people. The highest diagnosis rate occurred in 2013 at 2.97 per 100,000 people, while the lowest was recorded in 2020 at 1.7 per 100,000 people. The average monthly diagnosis cases of hepatitis C was 2291.
The diagnosis rate for hepatitis C was analyzed using the ARIMA model. Figure2 displays a time series analysis of hepatitis C diagnosis rate in Henan spanning from January 2013 to September 2022. The data is divided into two segments: pre-COVID-19 (from January 2013 to December 2019) and post-COVID-19 (from January 2020 to September 2022). The insights gained from Fig.2 highlight a noticeable decrease in hepatitis C diagnosis rate during the COVID-19 outbreak in 2020, followed by a subsequent increase. Across the broader timeframe from 2013 to 2022, the diagnosis series of hepatitis C exhibited cyclic patterns. Through the application of differencing to adjust for this trend and periodicity, the hepatitis C diagnosis series demonstrated enhanced stability.
Henan Province Hepatitis C Time Series Plot
The Box-Cox method was employed, along with the auto.arima function in the R software, to fit the hepatitis C diagnosis series in Henan Province from January 2013 to September 2022. ACF and PACF plots are depicted in Supplementary Fig.S1. In this illustration, bars above or below the dotted line represent statistically significant autocorrelation (P<0.05). Both ACF and PACF plots (Supplementary Fig.S1a) reveal undifferentiated autocorrelation and partial autocorrelation patterns, with noticeable significant autocorrelation. Supplementary Fig.S1b presents autocorrelation and partial autocorrelation post-differencing. In comparison to Supplementary Fig.S1a, differencing effectively removed much of the autocorrelation.
The ARIMA (0,1,1) (0,1,1)12 model yielded the lowest AIC (1459.58), AICc (1460.19), and BIC (1472.8). Consequently, this model structure was selected as the optimal. Diagnostic results indicated that for the ARIMA (0,1,1) (0,1,1)12 model, MA1=-0.62 (t=-8.06, P<0.001) and SMA1=-0.79 (t=-6.76, P<0.001); ACF and PACF plots of residuals indicated most correlation coefficients were within the confidence interval (Supplementary Fig.S2). The Ljung-Box Q test results demonstrated no statistically significant difference among residuals for different lag periods (P=0.408), affirming that model residuals constituted white noise. These results validate the ARIMA (0,1,1) (0,1,1)12 model.
Over time, the time series plot displayed relatively constant variance. The histogram of the time series showed normally distributed prediction errors, with the mean adhering to normal distribution as well. Residuals showcased no discernible pattern or significant autocorrelation, and they followed a normal distribution. The Ljung-Box Q test yielded a P-value of 0.408, confirming the chosen models good fit.
The final model estimated a step change of -800.0 (95% CI -1179.9 ~ -420.1, P<0.05) and a pulse change of 463.40 (95% CI 191.7~735.1, P<0.05) per month. Figure3; Table1 depict the comparison between predicted and observed values of the ARIMA model without intervention (counterfactual).
From January 2013 to September 2022, an analysis was conducted on the fitting and observed values of hepatitis C diagnosis cases both before and after the onset of COVID-19. The findings suggested a decrease in hepatitis C diagnosis cases in January 2020, with an anticipation of the impact being transient. Since January 2020, the influence of COVID-19 on hepatitis C diagnosis rate was modeled using a pulse function. Following the emergence of COVID-19, a decline in hepatitis C diagnosis cases was observed. A step function was utilized to fit potential long-term fluctuations in the number of hepatitis C diagnosis cases. The final model revealed a sudden reduction in diagnosis cases post the onset of COVID-19, followed by a gradual increase back to pre-COVID-19 levels. Given the nature of the intervention, we assumed an immediate decrease in diagnosis cases post-intervention (step change) and an accompanying pulse change. Hence, variables representing both types of impacts were incorporated into the model.
Moreover, when comparing the ITS-ARIMA model with the BSTS model (Fig.3), results indicated that the mean absolute percentage error (MAPE=19.95%) of the ITS-ARIMA models predictions was lower than that of the BSTS model (MAPE=25.7%). This implies that the prediction performance of the ITS-ARIMA model surpassed that of the BSTS model, demonstrating the formers superior predictive capabilities.
Observed and predicted values without intervention based on ITS-ARIMA model
