In short Article

Vaccines for COVID-19: an update


Since the beginning of 2021, two mRNA vaccines and two vector vaccines against SARS-CoV-2 have been available in the Netherlands, and a large proportion of the population have now been vaccinated. In the meantime, more information has emerged about their adverse effects, the duration of their effect, their effectiveness against new variants of the virus and the effects of booster vaccinations. Five new vaccines have been developed, some of which differ from the existing vaccines in a number of respects. Two of these new vaccines are so-called classic inactivated virus vaccines, and two of them are subunit protein vaccines, while the fifth is a vector vaccine. Four of these vaccines are currently being assessed by EMA. The remaining new vaccine (a subunit protein vaccine) has been authorized in December of 2021. The development of a third mRNA vaccine has been discontinued. 

  • The effectiveness of the vaccines against infection declines over a period of some months after vaccination. 
  • The vaccines offer less effective protection against infection by certain new variants of the virus.
  • A third vaccination (booster) increases the effectiveness of the vaccines in preventing infection, hospitalisation and mortality.
  • New inactivated virus and subunit protein vaccines, which are still being evaluated by EMA, target the original Wuhan SARS-CoV-2 virus, and they are probably less effective against the newer variants.
  • These new inactivated virus or subunit protein vaccines may represent an alternative if the use of the existing vaccines is impossible or undesirable. 

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Authors

  • Leo M.L. Stolk, dr