Deena Beesley

(Reuters) – A rising number of countries have reduced the waiting time for COVID-19 booster vaccines from six to three months in an effort to prevent a new wave in Omicron-related infections.

Omicron spreads faster than Delta’s predecessor and more easily infects people who are vaccinated. But some experts warn against giving vaccine boosters to too early because they could reduce the protection of long-term vaccinations.

Even though data are limited, half-a-dozen laboratory studies show that even though a two-dose initial COVID-19 vaccination isn’t enough to stop Omicron-related infection, booster shots may be beneficial.

Researchers from the UK and southern Africa have shown that Omicron is rapidly spreading, leading to predictions that the variant will outpace Delta within several countries. Scientists also want to know how severe Omicron can be.

Many countries, including the United States of America, allowed booster doses to be administered six months after vaccination was completed. South Korea and Thailand reduced this time period to three months last month. Belgium has reduced it to four.

France, Australia and Taiwan have reduced their waiting times for boosters by five months.

Some countries have stuck with the 6-month booster schedule, such as the United States and South Africa.

Finland recommended that at-risk patients receive a three month booster period. However, it stated that shorter time frames for general populations will not slow down rising hospitalizations.

Spain and Lithuania offer boosters for people who have weak immune systems. They also provide boosters to the elderly and vulnerable. India, however, has not yet decided whether it will launch a booster campaign. Due to rising numbers, the World Health Organization (which had advised wealthy countries to send first COVID vaccines to developing countries) has been more open to boosters.

Experts say that more information is necessary, however, shorter timeframes may pose a danger to the efficacy of multiple vaccine doses.

“In general, multiple-dose vaccines are more effective if there is time for the immune system to mature,” Dr. William Schaffner from Vanderbilt University School of Medicine said.

IMMUNE SYTEM DEFENSES

Although studies have shown that vaccine boosters can temporarily raise antibody levels, scientists believe the ultimate goal of any vaccine regimen should be to produce antibodies as well as second-line immunity system defenses like T-cells.

Baylor College of Medicine’s vaccine expert, Dr. Peter Hotez stated that “all that will be useful for keeping you out of hospital”

Multiple-dose vaccinations boost the immune system and give it enough time to mount back-up defenses.

Luciano Borio was a former chief scientist at the Food and Drug Administration. He said: “I worry that it might have an impact on the immune system maturation. This seems like an extremely short period of time.

Kristen Nordlund from the U.S. Centers for Disease Control and Prevention said that no changes are planned by the United States to its current recommendations for booster timing.

A spokesperson from Arkansas’ public-health department stated that “from an immunologic perspective, it doesn’t make sense to reduce the intervals to under six months.”

Experts argue, however, that the 6-month time period is arbitrary. However, data collected before the Omicron variant was introduced in November showed that antibody levels begin to decrease as early as four to six months following initial COVID-19 shots.

“Four months was when the waning started to be substantial,” Dr. Eric Topol from the Scripps Research Translational Institute La Jolla in California, said. Omicron only forces the problem.”