As Omicron threatens global boom, some countries shorten COVID-19 booster timelines

They are responding to early evidence that suggests Omicron is spreading faster than its predecessor Delta, and is more likely to infect people who were vaccinated or had COVID in the past. However, some scientists say that giving boosters too soon may compromise the level of protection from long-term vaccines.

While data remains limited, half a dozen laboratory studies have shown that an initial course of COVID-19 vaccines — usually given in two doses — is not enough to prevent infection with the Omron version, but a booster shot may help. Can do.

Research from southern Africa and the UK suggests that the variant is spreading very quickly, leading to speculation that it will soon overtake the delta in many countries. Scientists are also trying to figure out how serious Omicron’s cases are.

Several countries, including the United States, earlier this year authorized a booster dose six months after a person has completed vaccination. This month, South Korea, the United Kingdom and Thailand reduced that interval to three months. Belgium has reduced this to four months.

France, Singapore, Taiwan, Italy and Australia have reduced their booster waiting times to five months.

Some countries, including the United States, South Africa and Germany, are sticking to a six-month booster schedule.

Finland recommends a three-month booster timeline for at-risk groups, saying it does not believe that reducing the time for the general population will slow the rate of hospitalization.

Spain and Lithuania have also so far been offering boosters only to people with weakened immune systems, the elderly or vulnerable, while India has not decided on a booster campaign. The World Health Organisation, which told rich countries to prioritize sending the first COVID vaccine doses to developing countries, has become more open to boosters in light of rising cases.

More data is needed, but there is a risk that the shorter time frame could compromise the effectiveness of vaccines given in multiple doses, experts said.

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

immune system protection

While studies show that boosters temporarily raise antibody levels, scientists say the goal of a vaccine regimen is to protect not only antibodies but second-line immune systems such as T-cells.

“All of this will help keep you out of the hospital,” said Dr. Peter Hotez, a vaccine specialist at Baylor College of Medicine.

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

“What worries me is that we don’t know what effect the dosage might have on the maturation of the immune system. Three months seems like a very short interval,” said Dr. Luciano Borrio, acting chief scientist for the Food and Drug Administration.

The United States has no plans to change its current booster timing recommendations, Kristen Nordlund, a spokeswoman for the US Centers for Disease Control and Prevention, said in an email.

“From an immunological standpoint, there is no point in reducing the interval to less than six months,” said a spokesman for the Arkansas Department of Public Health.

Still, some experts argue that the six-month lag was arbitrary, and data collected before the rise of the Omicron edition in November showed that immunity, as measured by antibody levels, fell only four months after the initial COVID-19 outbreak. gets started. Vaccination.

“Four months is the time when the shortage really started to become substantial,” said Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla, Calif. “Omicron just bolsters the issue.”