Do all inviduals need two doses of Corona vaccine?

Corona virus pandemic surging across the world has infected more that 42 crore (140 million) people and has claimed the lives of more than 30 lakh (3 million) people till now. Within a year several vaccines have been developed against the virus. 

  Vaccines help our body to trigger rapid and strong immune response against a real infection (in this case the Corona virus). Vaccine helps formation of antibody secreting cells and also the formation of special type of white blood cells called memory B-cells. Memory B-cells can live for long time in our body. So, when an infection from a real pathogen happens, the memory B-cells can trigger antibody formation rapidly. An individual is therefore protected from the pathogen for a long time because of the memory B-cells in their body. 

The current recommendation for full vaccination from corona virus involves two doses of the vaccine. A good antibody and memory B-cell response is shown after second vaccine dose in people that were not infected previously with the corona virus. 

 A recent study published in "Science Immunology" journal showed that in individuals who had previously recovered from COVID-19 required a single dose of either Pfizer or Moderna vaccine to produce sufficient antibody and memory B-cell response. There was no significant increase in the immune response in these individuals after the second dose of the vaccine. 

Now, that most of the countries are trying  to vaccinate their citizens against the corona virus, the world is facing shortage of vaccine supply. This is primarily due to the limited rate of production of the vaccine. The above study, might help countries to make strategies for vaccinating people appropriately.

The researchers however caution that the study shows only the immune response of different individuals to the vaccine and not whether they were protected from the virus. Further large scale clinical studies are essential to examine one or two dose regimen.