Should you skip your second COVID-19 vaccine dose?

Vaccine uptake varies around the world, with some countries still experiencing higher rates of the first COVID-19 vaccine dose compared to a second dose, suggesting that some people may skip their second dose of the COVID-19 vaccine. A recent study suggests why this might not be a good choice.

Conventionally, the approval of new vaccines around the world has always been a lengthy and systematic process. From an immunological point of view, new vaccines must succeed in inducing the production of neutralizing antibodies, which are produced by specific immune cells, the so-called B cells, and which prevent virus infection of the body

Pfizer and Moderna Covid-19 vaccinations

Pfizer and Moderna vaccines work similarly in that they both contain the mRNA code required to make SARS-Cov-2 spike proteins. 1 SARS-Cov-2 is the scientific term for the virus that COVID-19 causes, and this virus uses spike proteins to infect its human host's cells.

The mRNA vaccines developed by Pfizer and Moderna work differently than conventional vaccines. Classic vaccines, for example, typically consist either of the prefabricated individual proteins themselves or of pathogens that increase the immune system's response to a specific microbe

Importance of the second dose

As a new milestone in the field of vaccinology, the emergency use of two mRNA vaccines was approved within one year of the pandemic outbreak.2 Finally, Dr. Pulendran, Professor of Pathology at Stanford University School of Medicine, "This is the first time humans have been given RNA vaccines."

According to a study conducted by researchers at Stanford University, a second dose of the COVID-19 vaccine was found to give people a powerful boost to the immune system.1 Such conclusions were drawn after analyzing a wide range of blood samples from people who had the Pfizer vaccine had been immunized.

Specifically, the researchers measured the complete gene expression of 242,479 different types of immune cells as well as the concentrations of antibodies and immune signal proteins in the blood samples

Should you skip your second dose of the COVID-19 vaccine?

The research team concluded that the first shot of the COVID-19 vaccine increased antibody levels for SARS-CoV-2 in the body, but not nearly as much as the second dose.3 Likewise, Dr. Pulendran that "the second vaccination" had strong positive effects that far surpassed those of the first injection … it stimulated a multifaceted rise in antibody levels, a great T-cell response that was absent after the first injection alone, and a strikingly heightened congenital one Immune response. "1

Surprisingly, the second dose of the vaccine was also found to mobilize a newly discovered group of first-responder cells classified as monocytes, increasing their numbers 100-fold in blood cells

Since this increase in monocytes has been specifically linked to the second shot of the COVID-19 vaccine, it has created an even greater incentive for the public to receive the second dose.


  1. Stanford medicine. (2021, July 19). Study shows why the second dose of the COVID-19 vaccine should not be skipped. EurekAlert!
  2. Polack, F.P., Thomas, S.J., Kitchin, N. et al. Safety and effectiveness of the BNT162b2 mRNA Covid-19 vaccine. The New England Journal of Medicine (2020).
  3. Arunachalam, P.S., Scott, M.K.D., Hagan, T. et al. Systems vaccinology of the BNT162b2 mRNA vaccine in humans. Nature (2021).
  4. Image by Wilfried Pohnke from Pixabay

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