Corona viruses that cause the common cold can infect people repeatedly, indicating that immunity to the new virus that causes “Covid-19” may be similarly short-lived.And in a new study published September 14 in the journal Nature Medicine, scientists monitored 10 individuals for more than 35 years, to determine the number of times they were infected with the four known seasonal corona viruses. Because these viruses – known as HCoV-NL63, HCoV-229E, HCoV-OC43, and HCoV-HKU1 – either cause mild cold symptoms or cause no symptoms at all, the team periodically checked the blood of the participants for antibodies to discover new cases of the common cold. Infection.
And when the blood samples show an increase in the number of antibodies that target a specific virus, compared to the previous samples, this means that the person’s immune system is fighting a new infection. The researchers determined how severe this shift in antibody levels would be to form a confirmed infection, rather than a random fluctuation.
The new data shows that immunity to other coronaviruses tends to be short-lived, with repeated infections occurring often after about 12 months, and in some cases, even earlier, according to Dr. Francis Collins, director of the National Institutes of Health (NIH), In a comment on the search.
In a few cases, the study authors found, infection occurred as early as six months and nine months after the previous infection.
The ten study participants were all part of the Amsterdam Studies (ACS), on HIV-1 infection and AIDS, a study of the prevalence and occurrence of HIV infection, and risk factors that began in the 1980s. The participants, all of whom were not infected with HIV, gave blood samples every three to six months throughout the study period, and provided 513 samples in total.
For the new study, the authors re-examined those samples for infection with the Coronavirus, especially looking for antibodies that target a specific part of the nuclear capsid of each virus – the hard shell of the protein that surrounds its genetic material, known as RNA.
Based on this analysis, the team found that each participant had from 3 to 17 cases of coronavirus during the study period, with infection occurring again every six months to eight years and nine months. Most of the time, infection with the Coronavirus occurred about a year after the previous infection.
The authors wrote: “We show that natural infections occur for all four seasonal corona viruses, indicating that it is a common feature of all human corona viruses, including SARS-CoV-2.”
Although the authors have not studied SARS-CoV-2 in their research, they argue that the trend seen among common coronaviruses is still extending to the new virus. The team explained that all common corona viruses, despite their belonging to the same family, are genetically and biologically distinct, so any common features between them may be “representative of all human corona viruses, including SARS-CoV-2.” However, we do not yet know if SARS-CoV-2 has the potential to infect humans like other viruses.
Moreover, “at least three caveats must be taken into account when interpreting this data,” Collins noted.
First, the participants’ fluctuating antibody levels do not tell us anything about whether they actually contracted the disease, with each repeated infection. Collins writes that the increase in antibodies “may provide precisely the response needed to convert a major respiratory disease into a mild cold or no disease at all.”
In theory, the four viruses could also have genetic mutations that allowed them to re-infect people. Participants may have some immunity to viruses through white blood cells, rather than antibodies alone.
Previously, Life Science reported that white blood cells known as B cells and T cells work together to identify foreign substances in the body, including viruses, and mobilize the immune system to fight pathogens in a variety of ways. The authors noted that “antibodies are only one marker of immunity, which is also likely to be affected by immunity to B cells and T cells.”
Collins writes that T cells and B cells may also contribute to immunity to SARS-CoV-2, although we don’t know how much. He said that as people gain immunity to the virus, either through natural infection or a vaccine in the future, it will be important to track how long this immunity lasts. People will likely need to be vaccinated on a frequent basis to keep the virus isolated from us, previously Live Science reported.
In the new study, the team also found that seasonal Corona virus infection occurs more often in the winter months than the summer months in the Netherlands, and they suggested that “Covid-19” may ultimately share the same seasonal pattern.
Other experts also predicted that “Covid-19” may spread annually after the end of the epidemic.