Incorporating the mutational landscape of SARS-COV-2 variants and case-dependent vaccination rates into epidemic models

Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various non-pharmaceutical interventions(NPIs)to contain the spread of COVID-19 brought the entire world to a halt.After almost a year of seemingly returning to normalcy with the world's quickest vaccine development,the emergence of more infectious and vaccine resistant coronavirus variants is bringing the situation back to where it was a year ago.In the light of this new situation,we conducted a study to portray the possible scenarios based on the three key factors:impact of interventions(pharmaceutical and NPIs),vaccination rate,and vaccine efficacy.In our study,we assessed two of the most crucial factors,transmissibility and vaccination rate,in order to reduce the spreading of COVID-19 in a simple but effective manner.In order to incorporate the time-varying mutational landscape of COVID-19 variants,we estimated a weighted transmissibility composed of the proportion of existing strains that naturally vary over time.Additionally,we consider time varying vaccination rates based on the number of daily new cases.Our method for calculating the vaccination rate from past active cases is an effective approach in forecasting probable future scenarios as it actively tracks people's attitudes toward immunization as active case changes.Our simulations show that if a large number of individuals cannot be vaccinated by ensuring high efficacy in a short period of time,adopting NPIs is the best approach to manage disease transmission with the emergence of new vaccine breakthrough and more infectious variants.

SARS-CoV-2 infection rates after different vaccination schemes:An online survey in Turkey

Objective:To identify effects of various nationwide vaccination protocols on the evolution of new SARS-CoV-2 infections among adult population and to evaluate the safety of mRNA(BioNTech/Pfizer)vaccine.Methods:Totally 10735 adult volunteers that received at least one dose of BioNTech/Pfizer or triple doses of CoronaVac participated in this cross-sectional-online survey between 1 and 10 September 2021.The information was collected covering a 5-month period from April 2021 to September 2021.Information about people who were vaccinated with only single and double dose CoronaVac were not included in this study.Results:At least one side effect after single and double dose of BioNTech/Pfizer and triple doses of CoronaVac were observed in 42.1%,42.5%and 10.9%,respectively.The most common side effects were shoulder/arm pain,weakness/fatigue,muscle/joint pain and headache.The side effects were the most frequent in single BioNTech/Pfizer,while it was the least in triple CoronaVac.The rate of positive PCR tests before vaccination was 17.6%,and decreased to 3.0%after vaccination.The rates of positive SARS CoV-2-PCR were 18.8%,3.5%,3.1%,0.5%and 4.6%in single BioNTech/Pfizer,double BioNTech/Pfizer,double CoronaVac+single BioNTech/Pfizer,double CoronaVac+double BioNTech/Pfizer and triple CoronaVac,respectively.While 1.8%of PCR positive COVID-19 cases needed intensive unit care in the pre-vaccination period,intensive care unit was required in 0%,1.5%,2.4%,0%and 4.2%after single BioNTech/Pfizer,double BioNTech/Pfizer,double CoronaVac+single BioNTech/Pfizer,double CoronaVac+double BioNTech/Pfizer and triple CoronaVac,respectively.Reinfection rate after vaccination was 0.4%.Conclusions:The rarity of COVID-19 infection after vaccination suggests that efficacy of vaccines is maintained.On the other hand,the data underscore the critical importance of continued public health mitigation.

Coverage rates for diphtheria,tetanus,poliomyelitis,and pertussis age-specific booster recommendations in France:2018 update of the real-world cohort analysis

The French National Immunization Program was updated in 2013 for vaccination against diphtheria,tetanus,per-tussis,and poliomyelitis.Our previous findings on the evolution of age-specific booster vaccination coverage rates(VCRs)up to 2017 suggested suboptimal vaccination coverages due to the pre-2013 recommendation-residual vaccination practices.In the current analysis,we evaluated all age-specific booster VCR and distribution of age at vaccination visits in 2018.In this retrospective observational cohort study,the cumulative booster VCRs were updated at all vaccination visits up to 2018 among the people who were eligible for a booster vaccination,using a 1/97th random sample of French national healthcare reimbursement databases.The cumulative booster VCR for individuals from all age groups increased from 2017 to 2018,except for 85-years-old vaccination visit.Majority of the individuals from all age groups were vaccinated(boosted)with a vaccine containing the pertussis valence.In 2018,sharp peaks corresponding to the recommended ages for booster vaccination visits were observed for individuals aged 6,11 to 13,25,45,and 65 years.Our study reiterates suboptimal coverages in France and implies the need for booster vaccination throughout life for the protection of the population.

Modeling and simulation of the spread of H1N1 flu with periodic vaccination

Influenza H1N1 has been found to exhibit oscillatory levels of incidence in large pop- ulations. Clear peaks for influenza H1N1 are observed in several countries including Vietnam each year [M. F. Boni, B. H. Manh, P. Q. Thai, J. Farrar, T. Hien, N. T. Hien, N. Van Kinh and P. Horby, Modelling the progression of pandemic influenza A （H1N1） in Vietnam and the opportunities for reassortment with other influenza viruses, BMC Med. 7 （2009） 43, Doi： 10.1186/1741-7015-%43]. So it is important to study seasonal forces and factors which can affect the transmission of this disease. This paper studies an SIRS epidemic model with seasonal vaccination rate. This SIRS model has a unique disease-free solution （DFS）. The value Ro, the basic reproduction number is obtained when the vaccination is a periodic function. Stability results for the DFS are obtained when R0 〈 1. The disease persists in the population and remains endemic if R0 〉 1. Also when R0 〉 1 existence of a nonzero periodic solution is proved. These results obtained for our model when the vaccination strategy is a non-constant time-dependent function.

PERMANENCE OF A SIRS EPIDEMIC MODEL WITH IMPULSIVE VACCINATION AND DISTRIBUTED DELAYS

In this paper, we consider a SIRS epidemic model with impulsive vaccination and distributed time delays. By the discrete dynamical system determined by the stroboscopic map, we obtain the exact infection-free periodic solution to the system. Further, using the comparison theorem, we prove that the infection-free periodic solution is globally attractive under an assumption. A sufficient condition for the permanence of the model is investigated.

GLOBAL STABILITY OF SIVS MODEL WITH SATURATION INCIDENCE, INFECTION AGE AND IMPULSIVE VACCINATED RATE

In this paper, an impulsive vaccinated strategy to eradicate SIVS epidemic model is studied. Since infection age is an important factor of epidemic progression, we incorporate the infection age into the model. In this model, we analyze the dynamic behaviors of this model and obtain that there exists an infection-free periodic solution which is globally asymptotically stable under a sufficient condition. Our results indicate that a short period of pulse or a large pulse vaccination rate is the sufficient condition for the eradication of the disease.