RIO DE JANEIRO, BRAZIL – During a live stream on YouTube, Oxford University Professor John Bell said that people who were infected with the novel coronavirus in March may now be prone to re-infections. According to Bell, Covid-19 antibodies can be depleted by between ten and 30 percent every month and they “quickly vanish”.
A recent study by King’s College London of approximately 90 people found that the antibodies faded over time, reaching a peak three weeks after the first symptoms and dropping rapidly thereafter.
As the virus is relatively new, it is still unclear whether or not a recovered patient can be re-infected. What is known is that in other cases of respiratory diseases caused by a coronavirus (such as SARS and MERS) a two-year immunity was developed. In other variations of the virus (such as OC43 and HKU1), people were immune for a certain period of time.
Earlier this month, the University of São Paulo (USP) reported the first case of Covid-19 re-infection in Brazil, when a 24-year-old nurse tested positive for the disease twice over a 50-day interval. Re-infections are rare and it is unclear how many such cases exist in the world.
A study released this week on the immune system response to Covid-19 shows that even without the production of antibodies against the virus, an individual can produce cells capable of destroying the disease in cases of re-infection. These are called T lymphocytes – reactive cells that help the body defend itself from infections.
However, in all cases immunity only lasts until a new strain of the virus emerges, since mutation is an inherent feature of this virus. This is the reason why an individual will have the flu more than once, for instance.
Source: Exame