Chances of COVID-19 attack after being vaccinated

Corona vaccination programs are going on in full swing in different countries of the world including Bangladesh. But there have been few reported cases of people who have been vaccinated, still testing positive for COVID-19. In this context, many people have a question in their minds -is there any chance of catching COVID-19 after getting vaccinated?

According to health experts, it is not abnormal for people to be infected after being vaccinated. Especially for those who have the Coronavirus in their body before they get vaccinated are most likely to be infected.

Also, by some other causes, some people can get COVID-19 after getting vaccinated.  Research is also underway to find out why some people are being infected with COVID-19 after getting the Corona vaccine and what the number of being infected after vaccination is.

An article in the New York Times on March 23, 2021, mentioned that there is a rare possibility of COVID-19 infection after being vaccinated. The article cited a survey result of hospital staff in Dallas, where only 4 out of 8,121 fully vaccinated (two doses) people became infected. The article also mentioned another survey result that observed just 7 out of 14,990 workers in California tested positive two or more weeks after receiving the Corona vaccine.

These surveys show that the number of Corona infections after vaccination is negligible. Bangladesh has not yet conducted a specific survey in this regard. Such a survey is very important to know more details about the Corona vaccination and its after-effects. We will now look into what are the chances of Corona's attack after being vaccinated.

Immunity forms after two to three weeks of vaccination
Vaccination is the safest and most common way to gain immunity against a bacteria or virus that one's body has yet to encounter. But after corona vaccination, it takes time to form immunity within the body. COVID-19 vaccines generate both antibody and T cell responses to form immunity against Coronavirus.

And only after the formation of necessary antibodies they begin to prevent the Coronavirus from entering the body or to kill the viruses present in the body. According to the US Centers for Disease Control and Prevention, some days to weeks are needed to form required antibodies within the body after the vaccination.

One of the members of the National Technical Advisory Committee of Bangladesh, former Vice-Chancellor of Bangabandhu Sheikh Mujib Medical University Prof. Nazrul Islam said it takes at least 3 weeks for the body to produce enough antibodies after taking the Corona vaccine. And immunity against COVID-19 is not created within the body before the formation of the required number of antibodies. Therefore, anyone can be infected with the Coronavirus after being vaccinated until the body develops immunity.

Coronavirus may be present in the body before the vaccination
If a person carries the Coronavirus before vaccination, then he/she is very much susceptible to COVID-19 even after being vaccinated. In this regard, Prof. Nazrul Islam said, those who were affected by COVID-19 after vaccinated in Bangladesh may carry the virus before the vaccination. These few people were vaccinated during the 14-15 days of dormancy period of the Coronavirus in the body. As a result, they have been caught by the COVID-19 although they got vaccine jab.

According to some studies, Coronavirus can remain dormant in an infected person for up to five days or more. According to the World Health Organization, the dormancy of Coronavirus is 14 days. However, some researchers claim that the Coronavirus may be in a dormant stage for up to 24 days. So even after getting vaccinated, anyone can be infected with the dormant Coronavirus in the body.

The time between two doses of Corona jab
Most of the Corona vaccines that have been administered throughout the world so far has two doses. The only single-dose of COVID-19 vaccine is Johnson & Johnson's Corona vaccine that is available in the United States. Some studies mention that after14 days of the first dose of the Pfizer vaccine, it can develop 52% immunity. In the case of Moderna vaccine, it can develop 50.7% immunity after 14 days of the first dose, and 74.1 percent immunity may be developed after the first dose of the Oxford-AstraZeneca vaccine.

So, it can be concluded that a person is not completely safe between the two doses of the Corona vaccine. Even some studies say that after the first dose of the Corona vaccine antibodies do not start to form in the body within 14 days. And after 14 days, antibody production begins, progressing step by step, and the full effectiveness of the vaccine is obtained after taking the second dose. Therefore, anyone can be infected with the Coronavirus during the interval of the two doses of the Corona vaccine.

No Corona vaccine is 100% effective
Experts say that no Corona vaccine is 100% effective. It is known that two doses of Pfizer vaccine will provide 95% protection against Coronavirus, so here the risk is 5%. An equal dose of Moderna vaccine will provide 94% protection, which means 6% risk. On the other hand, the Oxford-AstraZeneca vaccine is 70 to 90% effective and here the risk is 10 to 30%.

Since no Corona vaccine is 100% effective and so there is always a risk of being infected with Coronavirus after being vaccinated.No clear idea about the protection period of the Corona vaccine The length of time you are immune against disease through a vaccine may vary. Some vaccines give immunity for a lifetime after two or three doses, but other vaccines such as the influenza vaccine, require annual doses, called "boosters", to continue the protection.

In case of the COVID-19 vaccine, there is no clear idea on how long it will protect a person.However, research is underway on how long the Corona vaccine will help to protect a person from Coronavirus. According to the data available so far, the resistance to Coronavirus by a COVID-19 vaccine can be for at least six to eight months and could last for a year.Effects of new mutations and variants of Coronavirus

Each vaccine responds differently to viral mutations i.e. to new variants. Initially, the Corona vaccine producers expect that their vaccines to work well even against the new variants. But now the vaccine developers are concerned about the P.1 variant found in Brazil. This mutant variation has infected numerous people even though they had already been previously infected or vaccinated. The South African variant B.1.351 can also infect people who have been vaccinated, as medical experts were able to prove with the AstraZeneca vaccine.

From the above discussion, it is clear that even after being vaccinated a person may again develop COVID-19 symptoms. Just by taking the first dose of vaccine in Bangladesh, many people have given up the rules of following the COVID-19 guidelines. Relaxation comes from using masks, keeping social distance, or washing hands frequently. As a result, we can see the consequences. Corona infections are on the rise.

So, we all should adhere to the COVID-19 guidelines whether vaccinated or not yet been vaccinated. Wearing a mask, frequent hand washing with soap and water, and maintaining social distances - should be followed strictly and there is no way to be lazy or indifferent to at least these three rules of hygiene. And since no one is 100% safe even after vaccination, if any symptoms of COVID-19 appear after vaccination then that should be tested immediately, and a doctor's advice should be taken as soon as possible.


The writer is a Pharmacist and Doctoral Researcher of Massey University, New Zealand.