From UPSC perspective, the following things are important :
Prelims level : How vaccine works
Mains level : Paper 2- Breakthrough infections
- There have been several cases of Covid-19 vaccinated people, even those who have received both doses, testing positive for the virus.
- Such cases are referred to as “breakthrough” infections, indicating that the virus has been able to break through the defences created by the vaccine.
- Such cases have led to some doubts being expressed about the effectiveness of the vaccine, and contributed to the already prevailing vaccine hesitancy.
- However, vaccines protect not against the infection, but against moderate or severe disease and hospitalisation.
- It typically takes about two weeks for the body to build immunity after being vaccinated.
- So, the chances of a person falling sick during this period are as high — or as low — as the chances for any person who has not been vaccinated.
- Also, those in the priority list of vaccination, such as healthcare workers and frontline workers, have been prone to getting infected due to prolonged occupational exposure to the virus
Full protection not possible
- It is very well understood that no vaccine offers 100% protection from any disease.
- However, according to the Centers for Disease Prevention and Control (CDC) in the United States, vaccinated people are much less likely to get sick, but it is never entirely ruled out.
- Then there is the emergence of new variants of the virus.
- Some variants of the virus are able to evade the human immune response, and therefore have a greater chance to break through the defences created through the vaccine.
Breakthrough cases in India
- Among 10.03 crore people who had taken only the first dose of Covishield vaccina, 17,145 had got infected.
- That translates into a 0.02% prevalence.
- Among the 1.57 crore people who received the second dose as well, 5,014, or about 0.03%, had got infected later.
- About 1.1 crore doses of Covaxin have been administered until now.
- Of the 93.56 lakh who took only the first dose, so far 4,208 have got the infection.
- That is about 0.04% of the total.
- Among the 17.37 lakh who have taken the second shot, only 695 had been infected, again 0.04%.
- “Given the scope of the pandemic, there’s a huge amount of virus in the world right now, meaning a huge opportunity for mutations to develop and spread.
- That is going to be a challenge for the developers of vaccines.