Two studies suggest that you can get long-term immunity after being infected with COVID-19. People who previously had COVID-19 have high protective antibody titers for at least three months, and at six months still had persistent parts of the COVID-19 virus in their intestines that continued to cause high protection antibodies.
• One study showed that after you are infected with the virus or are vaccinated, you develop lasting B and T lymphocytes with viral neutralizing properties that can protect you for at least three months, and additional data with time will probably show much longer protection (Cell, Jan 7, 2021;184:169).
• The second study followed 87 patients who had proven COVID-19 infections (Nature, Jan 18, 2021). At 40 days they all had full protecting antibodies against COVID-19. After six months, they had 20 percent of the amounts of antibodies that were found at 40 days, but the six-month antibodies were more potent and could be more protective. At six months, seven of 14 patients also had COVID-19 virus remnants in their intestines.
Vaccinated People Can Skip Quarantine for Exposure to COVID-19
The U.S. Centers for Disease Control and Prevention (CDC) said on February 10, 2021 that those who have received the full course of COVID-19 vaccines can skip the standard 14-day quarantine after exposure to someone with the infection, as long as they remain asymptomatic. However, be aware that it may be remotely possible for a vaccinated person to transmit COVID-19 and infect someone else, even though they have no symptoms.
Data on Allergic Reactions to COVID-19 Vaccines
From December 14, 2020 through January 18, 2021, 66 allergic reactions occurred from 17,524,676 doses of the Moderna and Pfizer COVID-19 vaccines. That is an allergic reaction rate of about 6.6 cases per million doses administered (JAMA, February 12, 2021). Thirty-two percent of the 66 allergic reactions were in people who had had a prior episode of an allergic reaction to:
• vaccines (rabies, influenza A[H1N1], seasonal influenza, or unspecified)
• X-ray contrast media (gadolinium-based, iodine-based, or unspecified intravenous)
• unspecified injections
• sulfa drugs, penicillin, prochlorperazine, latex, walnuts, unspecified tree nuts, jellyfish stings
Current recommendations are that everyone should wait for 15 minutes after receiving a vaccine to see if an allergic reaction occurs, and those who have had previous allergic reactions to anything should wait for 30 minutes (MMWR Morb Mortal Wkly Rep, 2020;69(42):1522-1527). Common signs and symptoms in anaphylaxis cases include hives, diffuse red rash, swelling, difficulty breathing, or nausea. The personnel giving vaccines are always prepared to treat allergic reactions.