While some reports have come out saying antibodies to coronavirus go away quickly, a new study has revealed that the vast majority of individuals infected with mild-to-moderate COVID-19 mount a robust antibody response that is relatively stable for at least five months, other studies have shown that COVID-19 antibodies can be found even 9 months after the infection.
In one of the studies, published in the journal Science, it was found that this antibody response correlates with the body's ability to neutralize (kill) SARS-CoV-2, the virus that causes COVID-19.
Researchers from the University of Padua and Imperial College London tested more than 85 percent of the 3,000 residents of Vo', Italy, in February/March 2020 for infection with SARS-CoV-2, the virus that causes COVID-19, and tested them again in May and November 2020 for antibodies against the virus.
The team found that 98.8 percent of people infected in February/March showed detectable levels of antibodies in November, and there was no difference between people who had suffered symptoms of COVID-19 and those that had been symptom-free. The results are published today in Nature Communications. Antibody levels were tracked using three 'assays' - tests that detect different types of antibodies that respond to different parts of the virus. The results showed that while all antibody types showed some decline between May and November, the rate of decay was different depending on the assay.
The large differences in how one infected person may infect others in the population suggest that behavioral factors are key for epidemic control, and physical distancing, as well as limiting the number of contacts and mask-wearing, continue to be important to reduce the risk of transmitting the disease, even in highly vaccinated populations. The team's dataset, which includes the results of the two mass PCR testing campaigns conducted in February and March and the antibody survey conducted in May and then again in November, also allowed them to tease apart the impact of various control measures. They showed that, in the absence of case isolation and short lockdowns, manual contact tracing alone would not have been enough to suppress the epidemic.
The team also investigated the infection status of household members, to estimate how likely an infected member is to pass on the infection within the household. Their modeling suggests that there was a probability of about 1 in 4 that a person infected with SARS-CoV-2 passes the infection to a family member and that most transmission (79 percent) is caused by 20 percent of infections. This finding confirms that there are large differences in the number of secondary cases generated by infected people, with the majority of infections generating no further infections and a minority of the infections generating a large number of infections.
Also read: Delta Variant: Beware of Changing Symptoms
