How long will the COVID-19 vaccines provide protection from severe disease?

The best protection against COVID-19 illness is vaccination with one of the currently approved vaccines including the currently recommended single dose after previous documented COVID-19 illness. Protection against symptomatic  COVID-19 illness from current SARS-CoV-2 vaccines appears to begin to wane after about 4–6 months (JCVI 2021; PHE 2021). This is consistent with previous reports of waning of efficacy of mRNA vaccines against influenza virus (Connors et al 2021). 

Importantly, however, protection against severe COVID-19 illness appears to remain high to at least 6 month after vaccination, emphasising the value and benefits to individuals of SARS-CoV-2 vaccination. In Israel ~80.5% of the population have received a vaccination as of September 14 2021, daily infections are at their peak with 10,773 new infections reflecting reduced vaccine efficacy against the predominant Delta variant. Despite this, severe COVID-19 and deaths due to COVID-19 remain low among vaccinated individuals (See: https://www.thehindu.com/data/data-israels-recent-covid-19-spike-explained/article36402195.ece). A study conducted in the UK among almost 7 million adults vaccinated against COVID-19 found that an incidence of COVID-19-related death of ~0.002% (Hippisley-Cox et al 2021). Risk factors for COVID-19-related death or hospitalisation included Down’s syndrome, kidney transplantation, sickle cell disease, care home residency, chemotherapy, HIV/AIDS, liver cirrhosis, neurological conditions, recent bone marrow transplantation or a solid organ transplantation, dementia and Parkinson’s disease (Hippisley-Cox et al 2021).

Data collected in the UK by the University of Oxford and the Office for National Statistics indicates a marked waning of efficacy 4 months after the second dose of the Pfizer/BioNTech vaccine and a small but steady decrease for the Oxford/AstraZeneca vaccine for protection against symptomatic illness. However, the efficacy against symptomatic infection with the Delta variant for both the Pfizer/BioNTech and Oxford/AstraZeneca vaccine remained above 50%. Longer term data will be needed to determine to what extent and within what timeframe waning vaccine efficacy might translate into a resurgence of severe COVID-19 disease.