The study suggests that getting multiple doses of the updated COVID-19 vaccine can help the body produce antibodies that can fight off different variants of the virus and other related coronaviruses. The COVID-19 pandemic may be coming to an end, but the virus is still causing many people to get sick and is constantly creating new variants. Because the virus is so good at changing and dodging the immune system, the World Health Organization is suggesting that people get updated COVID-19 vaccines every year.
However, some scientists have concerns about the initial success of the first COVID-19 vaccines potentially hindering the effectiveness of updated versions and annual vaccination programs. This is similar to the problem seen with the annual flu vaccine, where immunity from one year’s flu shot can impact immune responses in the following years, decreasing the overall effectiveness of the vaccines.
A recent study conducted by researchers at Washington University School of Medicine in St. Louis aimed to explore this issue. Their findings revealed that, unlike immunity to the influenza virus, prior immunity to SARS-CoV-2, the virus responsible for COVID-19, does not impede later vaccine responses. The researchers have reported that repeated COVID-19 vaccinations can lead to the development of antibodies with broad inhibitory capabilities. The study, which can be found online in Nature, indicates that individuals who received multiple COVID-19 vaccinations, including shots targeting the original variant, boosters, and updated vaccines for new variants, produced antibodies that were able to neutralize a wide range of SARS-CoV-2 variants and even some distant coronaviruses. These findings suggest that regular COVID-19 re-vaccination may actually help people gradually build up a supply of broadly effective antibodies, rather than inhibiting the body’s ability to recognize and respond to new variants.Neutralizing antibodies offer protection against new strains of SARS-CoV-2 as well as other coronaviruses that may not have infected humans yet. This is because the first vaccine someone receives can create a strong initial immune response that shapes their responses to future infections and vaccinations. This phenomenon is known as imprinting, and in this case, the imprinting is positive because it is linked to the development of cross-reactive neutralizing antibodies.
Imprinting is a natural outcome of the way immunological memory functions. When someone receives a second vaccination similar to the first one, it triggers the memory cells produced by the first vaccine. These memory cells then control and influence the immune response to the second vaccine.
For the flu vaccine, imprinting has a negative impact. The memory cells that produce antibodies from the first vaccine suppress the production of new antibody-producing cells, resulting in fewer neutralizing antibodies against the strains in the newer vaccine.
In some cases, imprinting can have a positive impact by encouraging the development of cross-reactive antibodies that can effectively neutralize strains in both the initial and subsequent vaccines.
Diamond and colleagues, along with first author Chieh-Yu Liang, a graduate student, conducted a study to explore how imprinting affects the immune response to repeat COVID-19 vaccination. They analyzed the antibodies from mice or individuals who had received a series of COVID-19 vaccines and boosters, initially targeting the original and then omicron variants. Additionally, some of the human participants had previously been naturally infected with the virus that causes COVID-19.
Researchers initially sought to understand the strength of the imprinting effect. They accomplished this by measuring the number of participants’ neutralizing antibodies that were specific to the original variant, the omicron variant, or both. The results indicated that very few individuals had produced antibodies unique to omicron, suggesting a strong imprinting effect from the initial vaccination. Additionally, there were also few antibodies unique to the original variant, with the majority of neutralizing antibodies cross-reacting with both.
The subsequent question revolved around the extent of the cross-reactive effect. Cross-reactive antibodies, by definition, recognize a shared feature between two variants.One or more variations. Some characteristics are unique to specific variations, while others are common to all SARS-CoV-2 variations or even all coronaviruses. In order to gauge the range of neutralizing antibodies, the scientists tested them against a variety of coronaviruses, including SARS-CoV-2 viruses from two omicron lineages, a coronavirus from pangolins, the SARS-1 virus responsible for the 2002-03 SARS epidemic, and the Middle Eastern Respiratory Syndrome (MERS) virus. The antibodies were able to neutralize all the viruses except the MERS virus, which belongs to a different branch of the coronavirus family tree than the others.
Additional experiments demonstrated that this extraordinaryThe broad impact was a result of using both original and variant vaccines. Individuals who only received the vaccines designed for the original SARS-CoV-2 variant produced some cross-reactive antibodies that could neutralize the pangolin coronavirus and SARS-1 virus, but in low levels. However, after receiving a booster with an omicron vaccine, the cross-reactive neutralizing antibodies against the two coronavirus species increased.
Overall, the results indicate that regular revaccination with updated COVID-19 vaccines targeting variants may provide individuals with the means to combat not only the SARS-CoV-2 variants addressed in the vaccines, but also other virus species.SARS-CoV-2 variants and related coronaviruses are possible, including those that have not yet appeared. “At the beginning of the COVID-19 pandemic, the global population had no immunity, which contributed to the rapid spread and extensive damage caused by the virus,” explained Diamond, who is also a professor of molecular microbiology and pathology & immunology. “It is not certain whether receiving an updated COVID-19 vaccine annually would protect individuals from new coronaviruses, but it is a possibility. These findings indicate that if these cross-reactive antibodies do not diminish quickly, we should monitor their levels over time. time to know for certain — they may provide some level of protection against a pandemic caused by a related coronavirus.”
