People who have tested positive for COVID-19 may only need one shot of the vaccine, because their antibody response is higher than for people who have never been infected.
That is the conclusion of the latest research published in the ‘Journal of the American Medical Association’ this week.
The research involved about 4,000 respondents who were injected with the Pfizer or the Moderna vaccine; both vaccines utilizing the new mRNA technology.
According to Professor David Gordon, head of infectious diseases at Flinders University, the difference in responses between the two groups of respondents was immediately apparent.
“Seven days after vaccination, people who had not been infected with COVID-19 had no detectable antibodies at all. 14 days after vaccination, antibody levels started to rise,” he said.
“However, people who had tested positive previously, had a very large antibody response within seven days of being vaccinated,” added Professor Gordon.
Dr Larisa Labzin, a researcher at the Institute for Molecular Bioscience at the University of Queensland, said the research findings were not surprising.
“Basically, all vaccines try to trick the immune system into responding as if it had seen the virus before,” she explained.
“If you have contracted COVID, our immune system has recognized the virus and stored it in its arsenal, so it’s ready to respond,” she said.
That is why we receive two shots of the vaccine stated Dr Labzin. “We know the immune response is stronger with the second injection,” she said.
So far, it is not known how long the COVID-19 vaccine will be effective in a person’s body, or whether we are injecting ourselves more to protect from new variants.
Influenza, for example, requires a yearly flu shot because the virus mutates every year.
Professor Gordon explained that although the results of this study were encouraging, it did not examine the immune response in people who were given the second injection.
“There is always the question of how long immunity to the coronavirus will last. In principle, it depends on the memory of the immune response,” he explained.
“This research suggests there is a memory immune response (in people who have been vaccinated),” he added.
Given the current shortage of vaccines, this research currently suggests a single dose specifically for those who have contracted COVID-19.
However, the team of Australian immunization experts stated that people who have tested positive do not have additional risk from being vaccinated.
“We want to follow proven test studies. The third phase of clinical trials uses two doses. That is what has proven to be successful,” said Dr Labzin.
“There is no evidence that two shots of the vaccine for people who have had COVID will be dangerous,” she added.
Other research also published in the journal concluded that people who have been infected with COVID-19 have been well protected from being re-infected.
“Once we have an infection and our immune system has fought it, it won’t forget how to fight the infection,” explained Dr Labzin.
The body fights against viruses such as SARS-CoV-2 by binding antibodies to the virus, stopping them from entering cells and infecting the body.
Professor Gordon explained that after the body is first exposed to the virus, it takes a week or two to develop a good response.
“We know that if you are infected with COVID today, you do not get antibodies today. It takes weeks to develop a good immune response,” he explained.
“The immune system has memory capacity. So if we are exposed to the same virus six months later or years later, the immune response will emerge very quickly,” said Professor Gordon.