Evidence before this study The Pfizer–BioNTech mRNA COVID-19 vaccine BNT162b2, administered as two doses 21 days apart, was authorised for emergency use in Israel in December, 2020, after it was shown to have high efficacy against symptomatic laboratoryconfirmed COVID-19 in a randomised controlled trial of individuals aged 16 years and older. Since the initiation of vaccine rollout, we have been closely monitoring the scientific literature (including preprint servers) and press coverage to identify reports of BNT162b2 vaccine effectiveness. Although observational studies have estimated the effectiveness of BNT162b2, precise nationwide effectiveness estimates of two doses of BNT162b2 against SARS-CoV-2 outcomes are lacking. More data are particularly needed regarding the vaccine’s effectiveness against severe disease and deaths, and effectiveness in older adults. Finally, no country has yet described the nationwide public health impact of a national COVID-19 vaccination campaign. Added value of this study This analysis of nationwide surveillance data, done in a period when SARS-CoV-2 variant B.1.1.7 was the dominant strain, provides precise real-world estimates of the high effectiveness of two doses of BNT162b2 against a range of SARS-CoV-2 outcomes, including symptomatic and asymptomatic infection and hospitalisation or death due to COVID-19. The median follow-up time of 7 weeks after the second dose for vaccinated individuals was longer than that in previous reports. Marked and sustained declines in the incidence of SARS-CoV-2 infections were observed in all age groups as the percentage of individuals vaccinated with two BNT162b2 doses began to rise, thereby showing, at a national level, the beneficial public health impact of a nationwide vaccination campaign. Implications of all the available evidence Vaccination with two doses of BNT162b2 has high efficacy and effectiveness against a range of SARS-CoV-2 outcomes, including among older adults (aged ≥85 years), offering hope that COVID-19 vaccination will eventually control the pandemic. These findings are of international importance as vaccination programmes ramp up across the rest of the world, suggesting that other countries can similarly achieve marked and sustained declines in SARS-CoV-2 incidence if they can achieve high vaccine uptake.
Early in the pandemic, scientists engaged in a flurry of discussions about the best way to construct COVID-19 vaccines to ensure their efficacy and safety. Some of these discussions centered around antibody-dependent enhancement of immunity (ADE), a potentially deadly immune phenomenon seen with other viral infections and vaccines.
So far, there have been no reports of ADE with COVID-19 vaccines. But the concerns about ADE with COVID-19 vaccines have resurfaced with the emergency of virus variants. What exactly is ADE? What do we know from past experience with it? And why do experts say it's a non-issue with COVID-19 vaccines?
