The COVID-19 pandemic may be over, but the virus that caused it is still sending thousands of people to the hospital each week and producing new variants. The World Health Organization recommends annual updates to COVID-19 vaccines due to the virus’s ability to change and evade immune defenses. Some scientists worry that the success of the initial COVID-19 vaccines could undermine the effectiveness of updated versions, similar to the annual flu vaccine campaign.
A study by researchers at Washington University School of Medicine in St. Louis found that prior immunity to SARS-CoV-2, the virus that causes COVID-19, does not inhibit later vaccine responses. Instead, it promotes the development of broadly inhibitory antibodies. People who were repeatedly vaccinated for COVID-19 generated antibodies capable of neutralizing a wide range of SARS-CoV-2 variants and even some other coronaviruses. This suggests that periodic re-vaccination for COVID-19 may help people build up a stock of broadly neutralizing antibodies that protect them from emerging variants.
Imprinting, the result of immunological memory, plays a crucial role in how repeat COVID-19 vaccination influences the immune response. The researchers found that very few people developed antibodies unique to the omicron variant or the original variant, indicating strong imprinting by the initial vaccination. These cross-reactive antibodies neutralized a panel of coronaviruses, including variants from the omicron lineage, the SARS-1 virus, and a pangolin coronavirus, but not the MERS virus. Boosting with an omicron vaccine led to increased cross-reactive neutralizing antibodies against other coronaviruses.
Regular re-vaccination with updated COVID-19 vaccines targeting variants may give people tools to fight off not only the SARS-CoV-2 variants represented in the vaccines but also other related coronaviruses, possibly even ones that have not yet emerged. The research suggests that people may be protected against emerging coronaviruses with updated vaccines each year. If cross-reactive antibodies do not rapidly decrease over time, they may provide substantial protection against a pandemic caused by a related coronavirus.
The study provides valuable insights into how repeat COVID-19 vaccination influences the immune response and the potential benefits of periodic re-vaccination with updated vaccines. Understanding how prior immunity to SARS-CoV-2 affects vaccine responses is essential in developing strategies to combat variants and related coronaviruses effectively. The findings offer hope that regular re-vaccination may enhance the body’s ability to recognize and respond to new variants, ultimately providing broader protection against emerging viruses in the future.
