This content was published on December 20, 2021 – 6:07 pm
By Deena Beasley
(Reuters) – A growing number of countries are cutting the waiting time for COVID-19 vaccine boosters from six to just three months to fend off a new surge in infections from the Omicron variant.
They are responding to initial clues suggesting that Omicron is spreading faster than its predecessor Delta and is more likely to infect people who have been vaccinated in the past or who have had COVID. However, some scientists say that booster vaccination too early could compromise longer-term vaccination protection.
Although the data are limited, half a dozen laboratory studies have shown that initial treatment with COVID-19 vaccines – usually given in two doses – is not enough to stop the Omicron variant infection, but a booster dose can help.
Research from southern Africa and the UK shows the variant is spreading very quickly, leading to predictions that it will soon overtake Delta in several countries. Scientists are also trying to determine how serious the Omicron cases are.
Many countries, including the United States, approved booster doses six months after a person was vaccinated earlier this year. This month, South Korea, the United Kingdom and Thailand cut that interval to three months. Belgium has reduced it to four months.
France, Singapore, Taiwan, Italy and Australia have reduced their waiting time for boosters to five months.
Some countries, including the United States, South Africa, and Germany, have adhered to the six-month booster plan.
Finland has recommended a three month refresher period for risk groups and believes that reducing the time for the general population will not slow the increase in hospital admissions.
Spain and Lithuania have so far only offered boosters to people with weak immune systems, the elderly or people at risk, while India has not decided on a booster campaign. The World Health Organization, which advised rich countries to prioritize sending the first doses of COVID vaccine to developing countries, has become more open to booster vaccinations in the face of rising cases.
More data is needed, but there is a risk that shorter periods could affect the effectiveness of vaccines given in multiple doses, experts said.
“In general, with multiple-dose vaccines, the immune system works better when it has time to mature,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University School of Medicine.
DEFENSE OF THE IMMUNE SYSTEM
While studies show boosters temporarily increase antibody levels, scientists say the goal of a vaccine is to create not only antibodies, but also second-line defenses in the immune system like T cells.
“All of these will help keep you out of the hospital,” said Dr. Peter Hotez, a vaccines expert at Baylor College of Medicine.
Multi-dose vaccines strengthen the immune system and give it time to mobilize these supporting defenses.
Dr. Luciano Borio, a former senior scientist in the Food and Drug Administration, said, “I worry that we don’t know what effect the dose may have on immune maturation. Three months seems like a very short interval. “
The United States has no plans to change its current booster timing recommendations, spokeswoman for the U.S. Centers for Disease Control and Prevention Kristen Nordlund said in an email.
“From an immunological point of view, it doesn’t make sense to shorten the intervals to less than six months,” said an Arkansas Health Department spokesman.
However, some experts argue that the six-month interval was arbitrary, and data collected prior to the advent of the Omicron variant in November showed that immunity, as measured by antibody levels, was already four months after the first COVID-19 test. Illness decreases vaccinations.
“In four months the decline started to get really significant,” said Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla, California. “Omicron just enforces the problem.”
(Additional reporting by Carl O’Donnel and Michael Erman in New York; Olivia Kumwenda in Johannesburg; Aradhana Aravindan in Singapore; Rocky Swift in Tokyo; Ben Blanchard in Taipei; Krishna Das in New Delhi; Ari Rabinovitch in Israel; Francesco Guarascio in Brussels; Clara-Laeila Laudette in Madrid; Essi Lehto in Helsinki; Josephine Mason in London; arrangement by Caroline Humer, Michele Gershberg and Cynthia Osterman)