Should you vaccinate yourself against Covid-19?
D. Indumathi, The Institute of Mathematical Sciences, Chennai
Covid-19 cases are reducing all over India. However, scientists believe that there may be more "waves" or recurrences of this pandemic. Cases are high in many parts of the world. In contrast to last year, however, different vaccines are now available in India. The vaccination procedure has been expanded recently to include children above 12 years old. At the same time, we hear of people who have got Covid-19 after being vaccinated as well. Does this mean that vaccines don't work?
There are two effects of a vaccine. One is to prevent illness totally, to become immune to the disease. The other is its ability to reduce the severity of illness and even prevent death due to it. No vaccines have been shown to give 100% immunity to any person. Especially with the recent Omicron variant, which appears to be very efficient at evading our immune system and infecting us. However, all vaccines available in the world today appear to be useful in decreasing the intensity of the illness and preventing deaths. So it is important to take the vaccine. 
How do we know this? Many studies are on-going and the situation is made complex because of different immunity levels in different populations across the world, as well as different treatment approches, and the availability of different types of vaccines. A recent compilation of data from several countries around the world is very informative. It shows two different statistics : the number of Covid-19 cases over the last one year, and the number of deaths. Data of all countries is shown on the same vertical axis which correspondsto the daily cases per 1,00,000 lakh people (in blue) and daily deaths per 2 million population (in red).
The blue graph shows that cases have been rising in Hong Kong, Singapore, South Korea and Australia. However, the death rate shown in red is hardly visible for Singapore, South Korea and Australia. On the other hand, Hong Kong has fewer daily cases than these four countries; however, the death rate is much higher. In addition, the figure also shows the case fatality rate (number who died per 100 people) is 5.2% for Hong Kong and less than 0.1% for Singapore, South Korea and Australia.
Why is there such a high rate of deaths in Hong Kong even if the total number of cases is not large? One major reason could lie in the percentage of people who have been vaccinated in these countries. The figure shows the percentage of people who have not been vaccinated in each country : for instance, this number is less than 0.2% for Singapore, South Korea and Australia, but it is 66% in Hong Kong (so 2 of every 3 people in Hong Kong are unvaccinated). This clearly shows that vaccines may not be able to prevent infection from Covid-19 but can certainly help to reduce its impact.
While being infected with Covid-19 means that your body has developed anti-bodies to fight the virus, this kind of natural immunity may fade over time. The Covid-19 vaccines build up our anti-bodies and prevent the infection from becoming severe. That is, you may still get the virus after being vaccinated, but it may be mild and may not require hospitalisation and excessive drug treatments. This is also important when calculating the cost, not on the individual, but on the amount the government needs to spend to keep its population healthy.
Data source: Johns Hopkins University, USA