Adapted mRNA COVID-19 vaccines have a limited ability to establish herd immunity in the population against Omicron BA.1 and BA4-5 variants of SARS-CoV-2

Title : Adapted mRNA COVID-19 vaccines have a limited ability to establish herd immunity in the population against Omicron BA.1 and BA4-5 variants of SARS-CoV-2

Abstract:

The emergence of novel SARS-CoV-2 variants has raised concerns about the ability of COVID-19 vaccination programs to establish adequate herd immunity levels in the population. Adapted mRNA COVID-19 vaccines against BA.1 and BA.4-5 Omicron variants can provide a greater immunity against emergent SARS-CoV-2 variants than vaccines against the original variant. This study assessed the effectiveness of adapted vaccines in preventing SARS-CoV-2 infection and the ability of the adapted vaccines to establish herd immunity against emerging Omicron variants. Firstly, a systematic literature review was conducted to estimate the absolute vaccine effectiveness (aVE) in preventing SARS-CoV-2 infection using adapted vaccines targeting Omicron variants. Secondly, the ability of the adapted vaccines to establish herd immunity was assessed by taking into account the following factors: aVE, Ro values of SARS-CoV-2, and the use of non-pharmacological interventions (NPIs). The study found a meta-analysis based aVE in preventing severe disease and SARS-CoV-2 infection of 56−60% and 36−39%, respectively.

Nevertheless, the study found that the ability to block SARS-CoV-2 transmission was limited because they could not block the transmission of viruses with greater transmissibility. Firstly, the adapted vaccines could not establish herd immunity against the Omicron BA.1 and BA.4-5 variants without using non-pharmacological interventions (NPIs). Secondly, the adapted vaccines could establish herd immunity only by achieving >80% vaccination coverage, using NPIs with greater effectiveness and when a 20−30% percentage of individuals were already protected against SARS-CoV-2 in the population. New adapted COVID-19 vaccines with greater effectiveness in preventing SARS-CoV-2 infection must be developed to increase herd immunity levels against emerging SARS-CoV-2 variants in the population and reduce the health impact of emerging SARS-CoV-2 variants.

Biography:

Pedro Plans-Rubió has been Responsible for Health Registries, Public Health Agency of Catalonia, Health Department of Catalonia, Spain. He received his MD from the School of Medicine, University of Barcelona; his PhD from the School of Medicine, University of Barcelona, his MSc in Health Economics from the School of Economics, University of Barcelona, and his MSc in Design of clinical and epidemiological studies from the School of Medicine, University of Barcelona. Specialist in Preventive Medicine and Public Health. Specialist in Labor Medicine. Member of the research group CIBER of Epidemiology and Public Health (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain. He has published more than 100 articles in scientific journals on the epidemiology of infectious diseases, epidemiology of risk factors for chronic diseases and for infectious diseases, seroepidemiology, cost-effectiveness analysis of medicines and health programs, vaccination programs, and health policy. He has published more than 100 articles in scientific journals. He has published the book “Application of the cost-effectiveness of medicines and health programs in the health planning”, Elsevier, 2015. Editor-in Chief of Section “Vaccine Efficacy and Safety” of the journal Vaccines and Editor of several Special Issues of the journal Vaccines. Member of the Editorial Board of the journals Pharmacoeconomics Open.