American scientists believe that a single dose of the vaccine will generate large amounts of antibodies in people who have been infected with nCoV, enough to kill the variant virus.
With nearly 112 million cases of Covid-19 in the world, scientists always question whether or not to vaccinate those who have recovered. Recent studies have shown that people who have previously been infected with CoV still need to be vaccinated, but only one dose is effective for protection.
“The results are convincing,” said Jennifer Gommerman, an immunologist at the University of Toronto.
In the study published February 8, US scientists analyzed blood samples from a group of people infected with nCoV. As a result, their immune response to strain B1351 in South Africa is relatively poor. However, the amount of antibodies in the blood increased about 1,000 times after just one dose of vaccine Pfizer-BioNTech or Moderna. The duration of the retention of this antibody is unknown.
“This is a huge increase,” said lead researcher Andrew T. McGuire, Fred Hutchinson Cancer Research Center, Seattle.
With a large amount of antibodies, the patient samples of all volunteers participating in the study were able to inactivate B1351 and the corona strain that caused the SARS pandemic in 2003.
In fact, antibodies in infected people work more effectively than healthy people, or people who have received two doses of the vaccine.
The amount of memory cells capable of remembering and fighting nCoV also increased after the first dose, McGuire said. “Obviously, we are strengthening the body’s existing immunity”.
According to another study done by scientists from New York University on a group that had previously been infected with nCoV 8-9 months ago, the second injection only produced a small amount of antibodies. Meanwhile, the number of antibodies increased from a few hundred to thousands of times after the first dose. This phenomenon has also happened with other preventive vaccines.
Immunologist Florian Krammer, of the Icahn College of Medicine, New York, noted the importance of the study, but said the results were laboratory-based, unproven in practice.
The research he led showed that people with nCoV have more serious side effects after the first dose, the body produces more antibodies than the unvaccinated person.
“Combining all four reports, we get a pretty convincing amount of information confirming that people who have been infected with nCoV only need a single dose of vaccine,” Krammer stressed.
Krammer and other scientists are persuading the US Centers for Disease Control and Prevention (CDC) to recommend one dose of vaccine given to people who have previously had Covid-19. Health-care workers should continue to monitor people after the first dose, in case antibodies plummet after a few weeks or months, suggests immunologist Dennis R. Burton, Scripps Research Institute, California.
Le Hang (Follow NY Times)