Countries shorten COVID-19 booster timelines, as omicron threatens a global surge

In an effort to prevent a fresh outbreak of diseases caused by the Omicron variety, an increasing number of countries are lowering the wait time for COVID-19 vaccine boosters from six months to as little as three months. 

They’re reacting to preliminary findings that Omicron is spreading quicker than its predecessor, Delta, and is more likely to infect patients who have previously been vaccinated or had COVID. However, some scientists believe that administering boosters too soon may jeopardise long-term vaccine protection. 

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While the evidence is still limited, a half-dozen laboratory studies have found that an initial course of COVID-19 vaccines – generally given in two doses – is insufficient to prevent infection from the Omicron variety, but that a booster shot may assist.

According to research from South Africa and the United Kingdom, the variation is rapidly expanding, sparking predictions that it may soon overtake Delta in some nations. Scientists are also trying to figure out how severe Omicron cases are. 

Earlier this year, many countries, including the United States, authorized booster doses six months after a person had completed vaccination. South Korea, the United Kingdom, and Thailand reduced the gap to three months this month. It has now been reduced to four months in Belgium. 

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The wait time for boosters in France, Singapore, Taiwan, Italy, and Australia has been reduced to five months. 

The United States, South Africa, and Germany are among the countries that have adhered to the six-month booster schedule.

The United States, South Africa, and Germany are among the countries that have adhered to the six-month booster schedule. 

Finland has proposed a three-month booster period for at-risk populations, claiming that decreasing the duration for the general public will not help to reduce rising hospitalizations. 

Spain and Lithuania have likewise limited boosters to persons with weakened immune systems, the elderly, or those who are vulnerable, while India has yet to decide on a booster campaign. In view of growing cases, the World Health Organization, which previously advised rich countries to donate first COVID vaccination doses to underdeveloped countries, has become more open to boosters. 

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More research is needed, but experts warn that shorter time limits may jeopardise the efficacy of vaccines given in repeated doses.

“In general for multiple-dose vaccines … the immune system works better if it has time to mature,” Dr. William Schaffner, infectious disease expert from the Vanderbilt University School of Medicine, told Economic Times. 

While studies suggest that boosters improve antibody levels momentarily, scientists argue that the purpose of a vaccination regimen is to activate not only antibodies but also second-line immune system responses like T-cells. 

Dr. Peter Hotez, a vaccine expert at Baylor College of Medicine, said, “All that is going to be helpful for keeping you out of the hospital.”  

Multi-dose vaccines prime the immune system, giving it time to marshal those back-up defenses. 

Dr. Luciano Borio, a former Food and Drug Administration acting chief scientist, said, “I do worry that we don’t know what impact it may have on the immune system maturation of the doses. Three months seems like a very short interval.” 

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The United States has no plans to change its current booster timing recommendations, U.S. Centers for Disease Control and Prevention spokesperson Kristen Nordlund said in an email. 

“From an immunologic point of view, it does not make sense to shorten the intervals to less than six months,” said a spokesperson for Arkansas’ public health department. 

Still, some experts argue that the six-month interval was arbitrary, and data gathered prior to the rise of the Omicron variant in November has shown that immunity as measured by antibody levels begins to drop off as early as four months after initial COVID-19 vaccinations. 

“Four months is when the waning really started to get substantial,” said Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla, California. “Omicron just forces the issue.”