COVID-19 Vaccine Breakthrough Infections and Associated Factors in Kwekwe City, Zimbabwe, 2021

Background: To break the spread of COVID-19, people must adopt preven-tive health measures such as vaccination. A vaccine breakthrough infection is the detection of SARS-CoV-2 RNA or antigen in a specimen collected from a person ≥ 14 days after receipt of all recommended vaccine doses. Kwekwe City experienced an increase in breakthrough cases from one case (12 June 2021) to 39 cases (7 July 2021). The study was conducted to determine factors associated with breakthrough infections. Methods: We conducted an un-matched 1:2 case-control study. A case is defined as a patient who had two doses of a COVID-19 vaccine and had a positive SARS-CoV-2 antigen/PCR test at least two weeks after the date of receiving the second dose of the vac-cine in Kwekwe City from June 12, 2021. An interviewer-administered ques-tionnaire was used to collect data. We used the Epi Info software to generate means, frequencies, and proportions, to calculate measures of associations that include odds ratios. Results: Fifty-four cases in the records met the case definition for breakthrough infections, and two had died giving a case fatality rate of 3.7%. Fifty-one of the remaining 52 cases and 102 controls were re-cruited. Being within the age of 55 - 64 years (aOR = 12.22;95% CI (1.15 - 129.81) and being unemployed (aOR = 0.26;95% CI (0.07 - 0.93) were the independent factors associated with breakthrough infection. The median dura-tion in days between getting the second dose of the vaccine and getting tested was 57.0 (Q1 = 33;Q3 = 81) and 46 (Q1 = 33;Q3 = 64) for cases and controls respectively. There were significant differences in overall knowledge, controls had good knowledge compared to cases (p = 0.01). Conclusion: Individuals who were within the 55 - 64 years age group were more likely to have break-through infections. Those who had breakthrough infections had overall poor knowledge of COVID-19. Non-pharmacological interventions such as mask-wearing, social distancing, and frequent hand washing protect against having breakthrough infections. We recommended that residents get continu-ous education on the transmission, control, and prevention of the SARS-CoV-2 virus. The elderly should get booster doses of the vaccine.

Omicron variants breakthrough infection elicited higher specific memory immunity than third dose booster in healthy vaccinees

Homologous booster,heterologous booster,and Omicron variants breakthrough infection(OBI)could improve the humoral immunity against Omicron variants.Questions concerning about memory B cells(MBCs)and T cells immunity against Omicron variants,features of long-term immunity,after booster and OBI,needs to be explored.Here,comparative analysis demonstrate antibody and T cell immunity against ancestral strain,Delta and Omicron variants in Omicron breakthrough infected patients(OBIPs)are comparable to that in Ad5-nCoV boosted healthy volunteers(HVs),higher than that in inactivated vaccine(InV)boosted HVs.However,memory B cells(MBCs)immunity against Omicron variants was highest in OBIPs,followed by Ad5-nCoV boosted and InV boosted HVs.OBIPs and Ad5-nCoV boosted HVs have higher classical MBCs and activated MBCs,and lower naïve MBCs and atypical MBCs relative to both vaccine boosted HVs.Collectively,these data indicate Omicron breakthrough infection elicit higher MBCs and T cells against SARS-CoV-2 especially Omicron variants relative to homologous InV booster and heterologous Ad5-nCoV booster.

Postvaccination breakthrough SARS-CoV-2 infections among adults in Malaysia and attitudes towards future vaccination

Objective:To determine the frequency and severity of the breakthrough infections and the associated factors in Malaysia.Methods:This cross-sectional study was conducted among the adult general population in Malaysia who completed at least one dose of vaccination.The validated online questionnaires were used for data collection between December 2022 to February 2023.The participants were recruited by a convenient sampling method.The data were analysed by descriptive statistics,and logistic regression by using SPSS(Version 27).Qualitative data from open-ended questions were analysed as thematic analysis by using RQDA software.Results:A total of 524 participants'data were analyzed and 77.5%of them completed three doses of COVID-19 vaccination.Breakthrough infections after vaccination were reported in 57.3%of the participants.Age group of 18 and 30 years(aOR 2.32,95%CI 1.01-5.32)and other ethnicities(aOR 2.00,95%CI 1.02-3.93)significantly associated with the occurrence of breakthrough infections.A total of 35.5%of the participants were not willing to take another booster dose in the future because of their attitudes towards fear of long-term side effects,lack of trust to the vaccine,less susceptibility to severe infection,belief in natural immunity,and myths.Conclusions:Future public health policies and interventions should be focused on disseminating the information about safety of booster doses of vaccine,management and re-assurance of side effects,and targeted vaccination to the working(younger age group)and ethnic minorities.

Protective Effect of Neonatal Hepatitis B Vaccine Against HBV Breakthrough Infection in Children with Leukemia:A Real-world Study

Background and Aims:Hepatitis B vaccine is the most effective preventive measure against hepatitis B virus(HBV)infection.However,the risk of HBV breakthrough infection in fully immunized children(neonatal hepatitis B immunization)who receive immunosuppressive therapy and transfusion of blood components is not well characterized.In this real-world study,we aimed to investigate the immune protection conferred by neonatal hepatitis B vaccine in children with acute lymphoblastic leukemia(ALL)who were treated with immunosuppressive therapy and blood component transfusions.Methods:Children with ALL who had received all three doses of neonatal hepatitis B vaccine were included in this study.HBV seromarkers were detected before and after the initiation of immunosuppressive therapy.Results:A total of 1,011 children with ALL who were fully vaccinated against hepatitis B in infancy before the initiation of immunosuppressive therapy were eligible for inclusion.HBV infection was detected in four of 410 children(0.98%)with an HBsAg test after the initiation of immunosuppressive therapy.The median interval from treatment initiation was 19 months.Conclusions:Three doses of neonatal hepatitis B vaccine conferred adequate protection.In endemic regions,there is a low risk of HBV breakthrough infection in fully immunized children with immunosuppressive therapy.

Reinfection and Breakthrough Infection of SARS-CoV-2:An Emerging Challenge That Is Threatening Our World

The pandemic of coronavirus disease 2019 has threatened humans for more than one and a half years.In particular,viral mutation like delta strain has led to third-or fourth-wave transmission among the countries in Asia,Europe,and North America.Although large-scale vaccination has been carried out in many countries,the incidence of reinfection and vaccine-past breakthrough infection is becoming an emerging challenge to humans worldwide.The related mechanisms underlying the reinfection and breakthrough infection remain unknown.In this review,we summarized the challenge and related reasons for severe acute respiratory syndrome coronavirus 2 reinfection and breakthrough infection.Simultaneously,we addressed some critical contents of the study in future.

Global trends in COVID-19

The pandemic COVID-19 is certainly one of the most severe infectious diseases in human history.In the last 2 years,the COVID-19 pandemic has caused over 418.6 million confirmed cases and 5.8 million deaths world-wide.Young people make up the majority of all infected COVID-19 cases,but the mortality rate is relatively lower compared to older age groups.Currently,about 55.04%individuals have been fully vaccinated rapidly approaching to herd immunity globally.The challenge is that new SARS-CoV-2 variants with potential to evade immunity from natural infection or vaccine continue to emerge.Breakthrough infections have occurred in both SARS-CoV-2 naturally infected and vaccinated individuals,but breakthrough infections tended to exhibit mild or asymptomatic symptoms and lower mortality rates.Therefore,immunity from natural infection or vaccination can reduce SARS-CoV-2 pathogenicity,but neither can completely prevent SARS-CoV-2 infection/reinfection.Fortunately,the morbidity and mortality of COVID-19 continue to decline.The 7-day average cumulative case fatality of COVID-19 has decreased from 12.3%on the February 25,2020,to 0.27%on January 09,2022,which could be related to a decreased SARS-CoV-2 variant virulence,vaccine immunization,and/or better treatment of patients.In conclusion,elimination of SARS-CoV-2 in the world could be impossible or at least an arduous task with a long way to go.The best strategy to prevent COVID-19 pandemic is to expand inoculation rate of effective vaccines.As the population reaches herd immunity,the mortality rate of COVID-19 may continue to decrease,and COVID-19 could eventually become another common cold.

Comprehensive narrative review of real-world COVID-19 vaccines:viewpoints and opportunities

Currently,people all over the world have been affected by coronavirus disease 2019(COVID-19).Fighting against COVID-19 is the top priority for all the countries and nations.The development of a safe and effective COVID-19 vaccine is considered the optimal way of ending the pandemic.Three hundred and 44 vaccines were in development,with 149 undergoing clinical research and 35 authorized for emergency use as to March 15 of 2022.Many studies have shown the effective role of COVID-19 vaccines in preventing SARS-CoV-2 infections as well as serious and fatal COVID-19 cases.However,tough challenges have arisen regarding COVID-19 vaccines,including long-term immunity,emerging COVID-19 variants,and vaccine inequalities.A systematic review was performed of recent COVID-19 vaccine studies,with a focus on vaccine type,efficacy and effectiveness,and protection against SARS-CoV-2 variants,breakthrough infections,safety,deployment and vaccine strategies used in the real-world.Ultimately,there is a need to establish a unified evaluation standard of vaccine effectiveness,monitor vaccine safety and effectiveness,along with the virological characteristics of SARS-CoV-2 variants;and determine the most useful booster schedule.These aspects must be coordinated to ensure timely responses to beneficial or detrimental situations.In the future,global efforts should be directed toward effective and immediate vaccine allocations,improving vaccine coverage,SARS-CoV-2 new variants tracking,and vaccine booster development.

Recent SARS-CoV-2 Outlook and Implications in a COVID-19 Vaccination Era

While repurposed drugs came in handy earlier in the wake of the coronavirus disease 2019(COVID-19)pandemic,vaccination has been considered a more sustainable approach.The recent spikes have been linked to“double,”“triple,”and even multi-mutant variants,thus renewing calls for deeper structural and functional insights of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)as a lead to rationale design of therapeutics,vaccines,and point-of-care diagnostics.There is a repertoire of findings from the earliest SARS-CoV-2 molecular mimicry to evade host immunity cum host immune responses to the role of the viral glycocalyx in modulating the susceptibility and severity of infection through attraction and repulsive interactions.Recently,molecular studies of some viral components that aid infection in the face of vaccination seem unending.In addition,the wave of infections and the attendant case fatality ratios have necessitated the need for emergency use authorizations for COVID-19 vaccines and in vitro diagnostics.This review provides key updates of SARS-CoV-2,current antigenic and formulation strategies,with emergency use authorizations considerations for future vaccine candidates and diagnostics.We also premise that despite the difficulty in modeling and analyzing glycans,understanding and exploiting their roles in the SARS-CoV-2 architecture is fundamental to glycan-based COVID-19 vaccines devoid of inconsistent clinical outcomes.