To strengthen protection against the highly transmissible Omicron variant, several countries have expanded COVID-19 vaccine booster programmes or reduced the time between jabs. However, some experts argue that a fourth vaccine shot is unlikely to provide additional protection against viral infection, and that receiving too many COVID-19 booster shots may actually weaken our immune system.
Addressing a press briefing, experts from the European Medicines Agency (EMA) warned that booster shots should not be given too close together as it could potentially weaken our immune response.
Marco Cavaleri, the head of Biological Health Threats and Vaccines Strategy at the EMA, expressed concern about the repeated vaccination within a short term. He argued that giving a booster dose too frequently, say every 3 or 4 months, will potentially cause a problem with the immune response, and “the immune response may end up not being as good as we would like it to be.”
Last month, results of a preliminary research at an Israeli hospital also reported that a 4th vaccine shot doesn’t appear to produce enough antibodies to prevent infection from the Omicron variant.
The study included 274 medical workers at Sheba Hospital near Tel Aviv who received a fourth dose in December after previously being inoculated with three Pfizer-BioNTech shots. While 154 of them received the same Pfizer-BioNTech vaccine, the rest were given Moderna vaccine. Both groups experienced a slightly increase in antibodies, but that did not prevent the spread of omicron, the researcher stated.
Dr. Gili Regev-Yochay, director of Sheba Hospital’s infection disease unit, stated that while the fourth vaccine did provide increased antibody levels, it only offers a partial defense against the virus.
Mention may be made that Israel is offering COVID-19 second booster dose to those who work in healthcare and those above 60 years.
According to Dr. William Schaffner, an expert in infectious diseases at Vanderbilt University in Tennessee, the immune system needs some time to process the information it receives in the initial vaccination series. It is important to give the immune system time to ‘digest’ that information before giving another shot so that it can respond optimally, Schaffner told an American health information provider.
Meanwhile, authorities in South Korea have confirmed that the country will start giving fourth doses of COVID-19 vaccines this month amid a surge in Omicron infections.
High-risk groups, including those who live in nursing homes and care facilities and others with declined immunisation, will be the first to get the second booster shot, Health Minister Kwon Deok-cheol told a COVID-19 response meeting.
In a separate briefing, Korea Disease Control and Prevention Agency (KDCA) director Jeong Eun-kyeong informed that about 500,000 people aged 18 or older who live or work at care centres, and 1.3 million others who are immunocompromised would be given the fourth COVID-19 shot.
The US Centers for Disease Control and Prevention also recommends that people with weakened immune systems get a booster dose of the COVID-19 vaccine three months after finishing the initial series of Pfizer-BioNTech or Moderna shots, rather than the current five-month interval.
According to the agency’s updated guidance, immunocompromised people who received the one-shot Johnson & Johnson vaccine should receive an additional dose at least 28 days apart, followed by a booster dose of one of the mRNA vaccines.