COVID-19 Antibodies Likely Protect From Reinfection for Up to 120 Days

Illustration of antibodies (y-shaped) responding to a coronavirus infection. Different strains of coronavirus are responsible for diseases such as the common cold, gastroenteritis and SARS (severe acute respiratory syndrome). The new coronavirus SARS-CoV-2 (previously 2019-CoV) emerged in Wuhan, China, in December 2019. The virus causes a mild respiratory illness (Covid-19) that can develop into pneumonia and be fatal in some cases. The coronaviruses take their name from their crown (corona) of surface proteins, which are used to attach and penetrate their host cells. Once inside the cells, the particles use the cells’ machinery to make more copies of the virus. Antibodies bind to specific antigens, for instance viral proteins, marking them for destruction by phagocyte immune cells.
Norman Sharpless, MD, director of the NCI, presented new findings on how prior infections with SARS-CoV-2 may have some degree of presentation against being reinfected with the virus.

New data from the National Cancer Institute (NCI) suggested severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies appear to protect from reinfection, according to Dr. Norman Sharpless, director of the NCI, who presented these new findings in a press briefing released by the National Institutes of Health.

The referenced study collected serology data from more than 3 million individuals in the United States, of which 12% were positive for antibodies. At 90 days, the individuals who tested positive for SARS-CoV-2 antibodies had a 10 times lower rate of infection compared with those who were negative.

Testing positive for SARS-CoV-2 antibodies may have important implications for decision making. On a personal level, individuals with antibodies may rejoin the workforce or engage in other activities, such as care for elderly family members sooner than those without antibodies. On the public health level, individuals who lack antibodies may need to be prioritized for vaccination over individuals with the protective antibodies.

Currently, SARS-CoV-2 serology status has not been incorporated to recommended vaccination prioritization. On the basis of these data, it may be prudent to incorporate antibody status, especially as access to vaccines is currently limited.

Results from SARS-CoV-2 antibody testing may allow for predicting an individual’s risk for future infection, and therefore, can be prudent for incorporation with current SARS-CoV-2 screening programs.

Despite these encouraging results, an important and still unanswered question remains: how long does the protection against SARS-CoV-2 reinfection persist?

The study from the NCI only followed individuals for 120 days. It remains unclear whether the observed decrease of reinfection among those positive for SARS-CoV-2 antibodies will have long-term protection.

Regardless, data from this and other studies suggested that a SARS-CoV-2 infection provided strong immunity against reinfection for a minimum of several months, and this protective effect can be identified thorough antibody testing.

Further studies are needed for determining the duration of protection such that individuals can understand and assess their personal risk for reinfection from SARS-CoV-2.


SARS-CoV-2 Antibodies Can Protect from Reinfection, NCI Study Suggests. News Release. National Cancer Institute. Published December 21, 2020. Accessed January 14, 2021.