By Nancy Jiang ’23
Staff Writer
Several reports on how COVID-19 affects the immune system have emerged since the beginning of 2020, exploring topics ranging from the molecular mechanism of how the virus binds to our cells to the additional effects on those who have other medical concerns.
To understand how SARS-CoV-2 affects the immune system, we must closely examine the structure of its spike protein. Once the virus invades the body, spike proteins enter host cells. The protein does so by binding to a cell surface receptor called angiotensin-converting enzyme 2. The ACE2 and receptor-binding domains on proteins can be imagined as specific puzzles or Lego pieces shaped to fit each other. ACE2 can bind with S1, a subunit of SARS-CoV-2 spike protein, which induces its conformational change. The structure or shape of the “S1 puzzle piece” changes, leading to the transition of another subunit, S2. After the two changes in structure, the puzzle is complete, and the protein can successfully enter the cell. This oversimplified explanation shows how antibodies can prevent COVID-19 infection. Antibodies, or other “puzzles,” come into the system and take over the place that ACE2 means to occupy. Our immune system detects the virus and produces antibodies to prevent infection. This reaction explains why some infected COVID-19 patients are asymptomatic but can still transmit the virus: The antibodies produced by their immune systems win, but the virus is still present in their bodies.
A common misconception about immunity against COVID-19 is that those who recover from the virus have corresponding antibodies in their systems that can sufficiently combat possible future infections. A study funded by the National Institutes of Health tested whether antibodies could neutralize SARS-CoV-2 to the point at which further infection was prevented. Conducted by Dr. Davide Robbiani and Dr. Michel Nussenzweig at the Rockefeller University, the research studied blood samples from 149 volunteers who had recovered from COVID-19. Results revealed that only 1 percent of the samples had a high enough concentration of antibodies in their systems to neutralize the virus. Moreover, the antibodies will eventually disappear at a rate that is different for each individual. Therefore, it is important for those who have had COVID-19 to get vaccinated too. If they have received treatments involving monoclonal antibodies or convalescent plasma, they should wait 90 days and consult their doctors before the vaccination.
Since nationwide inoculation began in mid-December, the United States has administered more than 32 million doses of vaccines at a rate of approximately 1.3 million doses a day. That means 8 percent of the total U.S. population has received at least one dose of the vaccine.
College students are ranked second on the vaccination priority list after health care personnel, frontline workers, educational sector workers and elders. This means a Mount Holyoke student who wishes to receive their first dose will need to wait until April.
International students currently located outside of the U.S. will need to consider their vaccine options, as vaccine types approved in their own countries may not be authorized in the U.S. Currently, the Food and Drug Administration has only approved two mRNA vaccines: the Pfizer-BioNTech COVID-19 vaccine and Moderna’s COVID-19 vaccine, both of which require two doses for sufficient concentration of antibodies to stimulate immune responses. According to the Johns Hopkins Coronavirus Resource Center, different vaccines are not interchangeable, and neither the safety nor the efficiency of the combination of different vaccines has been evaluated.