The study, led by scientists at La Jolla Institute for Immunology at San Diego university in the USA, assessed elements of the immune response including antibodies and T-cells, and found the "immune memory" may last for at least eight months.
The authors claimed that this is the first study of its kind, incorporating antigen-specific antibody, memory B cell, CD8+ T cell, and CD4+ T cell measurements, out past 6 months post-infection.
Researchers also found that viral loads appear to be similar among COVID-19 patients with and without symptoms.
Someone's behavior, or lack thereof, such as poor hygiene and careers such as those in health care could also contribute to superspreading events because of increased contact with many different people.
Researchers from the University of Oxford tested 12,000 frontline workers for COVID-19 antibodies. This includes cells that produce targeted antibodies that can stick to the virus in order to stop it - and T cells that can attack just the cells infected with the virus, called the cellular response.
Researchers said that staff with antibodies were also less likely to test positive for COVID-19 without symptoms, with 76 without antibodies testing positive, compared to only three with antibodies.
During the study, 89 out of 11,052 staff without antibodies developed a new infection with symptoms, while none of the 1,246 staff with antibodies developed a symptom infection.
In this study, a research team at the Medical Center - University of Freiburg in Germany found that after recovery from SARS-CoV-2 infection, immune cells are formed which remain in the body and could mediate a rapid immune response in case of reinfection.
But none of the three became unwell.
In isolated cases of recurrence of COVID-19, illness with the SARS-COV-2 virus has raised concerns that potential remission may be short-lived and recur.
Analyzing the results from the SARS-CoV-2 studies showed that the average length of time of viral RNA shedding into the upper respiratory tract, lower respiratory tract, stool and serum were 17 days, 14.6 days, 17.2 days, and 16.6 days, respectively.
The staff tested were followed for up to 30 weeks. It will not learn and it will not give us immunity to the coronavirus.
But Dr Rupert Beale at the Francis Crick Institute pointed out that this equated to "only a very small proportion of adults (less than 10%, maybe much less than 10%)" who would be protected by pre-existing T cell immunity.
For the past nine months, COVID-19 has been spreading from person to person in the US while scientists and medical professionals scramble to figure out the novel virus' patterns. Later, it was observed that most of these individuals had the immune cells to fight against the virus and prevent reinfection.