Covid vaccine in UAE: Immunity takes time to kick in after jab, say doctors

Dubai - People can be exposed to Covid right before being vaccinated, or right after, and there may not be time for the body to boost its defenses.

By Nandini Sircar

Published: Tue 12 Jan 2021, 10:33 AM

It takes time for vaccines to build up immunity, and the two authorised coronavirus vaccines in the country require two doses before the immunity to develop, UAE doctors have said.

Immunity does not kick in right away given the two doses both of the Pfizer-BioNTech and Sinopharm vaccines are administered several weeks apart, to train the body's immune system.

People can be exposed to coronavirus right before being vaccinated, or right after, and there may not be time for the body to boost its defenses.

Dr Muhammed Shafeeq, Specialist-Pulmonology, Aster Hospital, Al Qusais, said: “It takes time for the vaccine to build up immunity- usually one to two weeks after the second dose. The authorised corona vaccine requires two doses, given three to four weeks apart to train the body’s immune system. People can be exposed to corona virus right before being vaccinated or right after and there won’t be time for the body to develop its immunity.”

He added: “Usually, patients develop symptoms of Covid-19 two to 14 days after infection. For the vaccines to build up immunity, it takes a couple of weeks after the second dose. So the patients who were asymptomatic at the time of vaccination can develop symptoms as they would not have developed immunity to the virus at that time.”

No vaccine is 100 per cent effective, and the makers of coronavirus vaccines are still evaluating whether the shots protect against all infections, or just those that cause symptoms.

Dr Anthony Thomas, Director Diagnostic Division and Pathologist with Prime Healthcare Group, pointed out: “Immunity can be assured only after a few weeks of vaccination or after the second dose. Also the efficacy of vaccine varies from 75 to 85 per cent and does not assure immunity in everyone. However, this is sufficient to provide herd immunity and will help in building a safe community.”

Overall, both vaccines provided sufficient protection in clinical trials.

Dr Vinod Kumar, Specialist Internal Medicine Prime Medical Centre, Reef Mall Branch Deira Dubai, underlined: “The Centres for Disease Control and Prevention says building immunity ‘typically takes a few weeks’. The 95 per cent efficacy number for the Covid-19 vaccines also assumes some built-in wait time. For example, Pfizer measured the efficacy of its vaccine starting seven days after the second dose.”

Meanwhile, the doctors have explained that the current coronavirus vaccines cannot infect anyone with the virus. They don't contain the virus.

“Neither the recently authorised and recommended vaccines nor the other Covid-19 vaccines currently in clinical trials can cause you to test positive on viral tests”, added Dr Jacob Cherian, Specialist Internal Medicine and Medical Director for Medcare Medical Centres.

Instead, they carry a small stretch of genetic material known as messenger RNA or mRNA.

This instructs cells in the body to make a small piece of material that looks like a part of the virus. Those bits, in turn, get recognised by the immune system as a foreign invader and it starts to make antibodies and immune cells that can recognise and neutralise the virus if the vaccinated person ever gets exposed.