Health-care workers received the first doses of the COVID-19 vaccine in December 2020. A study by researchers at Washington University School of Medicine in St. Louis has found that repeat vaccination with updated versions of the COVID-19 vaccine promotes the development of antibodies that neutralize a wide range of variants of the virus that causes COVID-19, as well as related coronaviruses. Credit: Matt Miller/Washington University
_____________________________________________________________________________________________

The COVID-19 pandemic is over, but the virus that caused it is still here, sending thousands of people to the hospital each week and spinning off new variants with depressing regularity. The virus's exceptional ability to change and evade immune defenses has led the World Health Organization (WHO) to recommend annual updates to COVID-19 vaccines.

But some scientists worry that the remarkable success of the first COVID-19 vaccines may work against updated versions, undermining the utility of an annual vaccination program. A similar problem plagues the annual flu vaccine campaign; immunity elicited by one year's flu shots can interfere with immune responses in subsequent years, reducing the vaccines' effectiveness.

A new study by researchers at Washington University School of Medicine in St. Louis helps to address this question. Unlike immunity to influenza virus, prior immunity to SARS-CoV-2, the virus that causes COVID-19, doesn't inhibit later vaccine responses. Rather, it promotes the development of broadly inhibitory antibodies, the researchers report.

The study, available online in Nature, shows that people who were repeatedly vaccinated for COVID-19—initially receiving shots aimed at the original variant, followed by boosters and updated vaccines targeting variants—generated antibodies capable of neutralizing a wide range of SARS-CoV-2 variants and even some distantly related coronaviruses. The findings suggest that periodic re-vaccination for COVID-19, far from hindering the body's ability to recognize and respond to new variants, may instead cause people to gradually build up a stock of broadly neutralizing antibodies that protect them from emerging SARS-CoV-2 variants and some other coronavirus species as well, even ones that have not yet emerged to infect humans.

more ...