Coronaviruses that cause the common cold can infect people repeatedly, suggesting that immunity to the new coronavirus that causes COVID-19 may be short-lived.
In a new study, published Sept. 14 in the journal Medicine of nature, scientists monitored 10 individuals for more than 35 years to determine how often they were infected by the four known seasonal coronavirus. Because these viruses – known as HCoV-NL63, HCoV-229E, HCoV-OC43, and HCoV-HKU1 – cause mild symptoms of the common cold or have no symptoms at all, the team periodically examined the participants’ blood for antibodies to identify new cases of infection.
When blood samples show an increase in the number of antibodies targeting a specific virus, compared to previous samples, it means that the person immune system he̵
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“The new data shows that immunity to other coronaviruses tends to be short-lived, with reinfections occurring quite often about 12 months later and, in some cases, even earlier,” Dr. Francis Collins, director of the National Institutes of Health (NIH), written in a research comment. In some cases, reinfections occurred as early as six months and nine months after a previous infection, the study authors found.
The 10 study participants were all part of the Amsterdam Cohort Studies (ACS) on HIV-1 Infection and AIDS, a study on the prevalence, incidence and risk factors for HIV infection that began in the 1980s. . Participants, all HIV negative, provided blood samples every three to six months during the study, providing 513 samples in total.
For the new study, the authors re-examined those samples for coronavirus infections, specifically looking for antibodies that target a specific portion of each virus’s nucleocapsid, the hard shell of proteins that surrounds their genetic material, known as RNA.
Based on this analysis, the team found that each participant contracted three to 17 coronavirus infections during the study period, with reinfections occurring every six months for up to eight years and nine months. Most often, however, reinfection of a particular coronavirus has occurred about a year after the previous infection.
“We show that natural-infected reinfections occur for all four seasonal coronaviruses, suggesting it is a common feature of all human coronaviruses, including SARS-CoV-2,” the virus that causes COVID-19, the authors wrote. .
Although the authors did not study SARS-CoV-2 in their research, they argue that the trend seen among common coronaviruses may still extend to the new virus. All common coronaviruses, despite belonging to the same family, are genetically and biologically distinct, so any trait shared between them could be “representative of all human coronaviruses, including SARS-CoV-2,” the authors wrote. That said, we still don’t know if SARS-CoV-2 has the potential to reinfect humans as often as others do.
Additionally, “at least three caveats should be kept in mind when interpreting this data,” Collins noted.
First, the participants’ fluctuating antibody levels tell us nothing about whether they actually fell ill with each reinfection. The increase in antibodies “may have provided exactly the answer needed to convert significant respiratory disease into a mild case of cold or no illness,” Collins wrote. In theory, four is also possible virus they may have had genetic mutations that allowed them to reinfect people. And the participants may have had some immunity to the viruses through their white blood cells, rather than their antibodies alone.
White blood cells known as B cells and T cells work together to recognize foreign substances in the body, including viruses, and mobilize the immune system to fight off pathogens in a variety of ways, Live Science previously reported. “Antibodies are only a marker for immunity, which is likely also affected by B- and T-cell-mediated immunity,” the authors noted.
T and B cells may also contribute to immunity against SARS-CoV-2, although we don’t know how much, Collins wrote. As people gain immunity to the virus, either through natural infections or a future vaccine, it will be important to keep track of how long that immunity lasts, he said. It is possible that people will need to be vaccinated on a recurring basis to keep the virus at bay, Live Science previously reported.
In the new study, the team also found that seasonal coronavirus infections occur more often in the winter months than the summer months in the Netherlands, and suggested that COVID-19 may eventually share the same seasonal pattern. Other experts have also predicted that COVID-19 could circulate every year after the pandemic ends.
Originally published in Live Science.