Public Health

Already Had COVID-19? You may only need one dose of the vaccine

Spencer Lee
Spencer Lee23 Mar 2021

Quick Digest: 

  • People who have already been infected with Covid-19 should still be vaccinated; however, one study suggests that one dose may suffice in conferring immunity.
  • Covid-19 survivors have reported fatigue, headache, chills, fever, muscle pain, and joint pain after the first dose more frequently than people who have never been infected with Covid-19. Furthermore, Covid survivors also demonstrated higher concentrations of antibodies than people who have never been infected after the first and second doses of the vaccine.
  • Because of these higher antibody levels, some scientists say that Covid survivors may only need one dose of the Covid-19 vaccine. This differs from people who have never had Covid, who will need to acquire two doses of the Pfizer or Moderna Covid-19 vaccines.


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Here’s what you need to know about getting the vaccine after having COVID-19

The Covid-19 vaccines created by Pfizer-BioNTech and Moderna are over 94% effective at preventing coronavirus infections. 

This was proven in large-scale clinical trials, and although these vaccines were developed in record time, they are completely safe. 

Both vaccines require two doses, spaced three to four weeks apart; however, some studies suggest that people who have already been infected with Covid-19 may only need one dose of either of these vaccines. 

This is because Covid-19 survivors have demonstrated higher antibody levels after receiving the first and second doses of the vaccine. Therefore, these increased levels of antibodies may be able to suffice to confer enough immunity to a Covid-19 survivor.


If I already had COVID-19, do I only need one dose of the vaccine?

One study determined that the antibody levels among Covid survivors after the first dose were comparable to the second dose among people who have never been infected. In laboratory experiments, these antibodies bound to Covid-19 molecules and prevented them from entering cells and causing infection. 

Because of these findings, the authors concluded with the suggestion that Covid-19 survivors should not only receive one dose and be moved down on the list of phased distribution.

Furthermore, one study concluded that surviving natural coronavirus infection confers 83% protection from getting reinfected within the span of five months. Coupled with a dose of the vaccine, which would act as a “second dose” for Covid survivors, this immunity may suffice for protection. 

Of course, more extensive research is needed before any conclusions can be made and policies set in stone. Some researchers have pointed to the fact that antibody levels differ among people who have already had Covid. 

For instance, somebody with a mild case is less likely to have high levels of antibodies as in the case of somebody who had a severe case of Covid-19. Therefore, if the person who only had mild Covid-19 symptoms only received one dose of the vaccine, they may not necessarily be immune from infection.

Additionally, new coronavirus mutants are becoming increasingly prevalent. Should one of these mutants be more infectious, it is possible that one dose of the vaccine will not be enough to protect previously infected individuals from re-infection.

Ostensibly, this is a complicated public health and ethical issue relating to resource allocation and prioritization. As vaccine shortages become more pressing, allocating a single vaccine to people who have already had Covid-19 would not only reduce pain and time spent accessing the vaccine itself but also free up additional vaccine doses for other individuals. 


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This is why some COVID-19 survivors report having increased side effects after vaccination

Side effects after receiving a vaccine are normal — and indeed positive — signs of an immune response. They indicate that your body recognizes the vaccine and is actively working towards building immunity that will protect you in the future. 

During the clinical trials of both the Pfizer and Moderna coronavirus vaccines, most participants reported at least some side effects after vaccination. Ranging from headaches to chills to soreness at the vaccination site, these side effects demonstrate that it is completely normal to encounter discomfort after vaccination. 

Regardless, for many people who have already had Covid-19, the side effects after vaccination have been more vigorous. One study examined the difference in side effects between people who had previously had coronavirus and people who did not. It found that both groups experienced some soreness at the injection site, but the people who were previously infected with coronavirus were more likely to experience symptoms such as fatigue, headache, and fever. 

For scientists, this is an unsurprising trend. Both vaccines contain the genetic material that allows our body to manufacture the spike proteins outside of the coronavirus molecules. 

Since people who have already been infected have the immune cells that target and kill the coronavirus, when they see the spike proteins that are normally found on coronavirus molecules, they go into attack, thereby causing a vigorous immune response that the individual feels as soreness, fevers, fatigue, etc. 

Of course, this is not meant to deter anybody from receiving a dose of the coronavirus vaccine. If eligible, you should seek vaccination. More research is needed on whether it will be safe to receive a sole dose if you have already been infected with the coronavirus.



Spencer Lee

Spencer is a Public Health & Biology undergraduate student at New York University.