COVID-19 vaccine efficacy drops after four to six months

Oman Wednesday 22/December/2021 23:30 PM
By: Times News Service

Muscat: Doctors in Oman have said that the effectiveness of COVID-19 vaccines declines after about four to six months, making it all the more important for people to sign up for booster shots.

People in the country aged 18 and above have been asked to sign up for third doses, particularly in the wake of the arrival of the Omicron variant.

“Scientific studies have shown that antibodies begin to decrease after a period of five to six months after vaccination with the Pfizer vaccine and four to five months after vaccination with the AstraZeneca vaccine, indicating that it was reliant on the effectiveness of memory and long-term immune T-cells to do their work in protecting the person from infection even with low B-antibodies,” said Dr Faryal Al Lawati, the head of the Infectious Diseases Unit, and a senior consultant in infectious diseases, at the Royal Hospital.

“There is an urgent need at the present time for a third dose, as the effectiveness of two doses of vaccination against the Omicron mutant to prevent infection, according to initial studies, may reach only 30 per cent,” she added.

Lower vaccine efficacy against the new COVID variant is due to the large number of mutations in the new strain, she explained, making a booster dose crucial towards strengthening the immune system and raising effectiveness.

Al Lawati referred to the current rapid spread of Omicron in Europe as evidence of the impact the new strain can have on countries.

“The strong ability of the Omicron mutant to spread created real fear, especially for healthcare systems, as we can see from the situation in Europe, where the number of infections have increased in an unprecedented manner,” she revealed.

“Many health centres have been forced to close essential medical services,” she further said.
Immunity responses are often particularly low among immune-compromised individuals, transplant patients, cancer patients, and those suffering from HIV, making it critical for them to get booster shots.

“Some people question the efficacy of vaccines in the same manner in which they questioned the impact of the virus at the beginning of the pandemic, but by recalling the previous waves that swept us and the rest of the world, let us remember what helped us get out of them: societal commitment to two factors, namely preventive measures, and vaccinations.” Adding to this, Dr Zaid Al Hinai, a consultant in infectious diseases at Sultan Qaboos University Hospital, said that the booster dose is an “excellent and powerful weapon” to prevent spikes in infections and hospitalisation rates, which in turn could lead to strict measures being taken once again to stop the spread of the virus.

“Many countries witnessed significant increases in COVID infections, as well as deaths and hospital admissions, forcing them to close,” he said. “With the spread of the Omicron strain in Oman, we do not want the same scenario to happen to us.”

“The truth is that getting vaccinated is a very simple procedure: it is efficient and safe, which makes it one of the simplest and most powerful solutions against the pandemic,” added Al Hinai. “If you are going to wait until you are boostered, know that the virus does not wait for you.”

In this context, Dr Zakaria Al Balushi, an inflammatory and infectious diseases consultant at the Royal Hospital, said that while the epidemiological situation in Oman is currently stable, keeping that way will require people to come forward and get their booster shots.

“The number of infections here are low, as are the numbers of inpatients and deaths, and no new deaths have been recorded in our country for a long time,” he said. “To maintain this good situation, prevention is necessary, and the best step we can take right now against Omicron is getting our target groups vaccinated with the third dose.”

“The importance of this lies in the continuity of normal life, and the stability of the current epidemiological situation,” he added, before asking people to not pay attention to malicious rumours and false news about vaccines that some choose to spread.

Dr Reda Al Lawati, an internist at the Royal Hospital, described a case study involving an Omicron-infected patient in Canada, which showed that the new mutation infected three more people on average, as compared to the Delta variant.

“Another study in Britain showed that two doses of AstraZeneca vaccines only offer 20 per cent protection against Omicron, while Pfizer’s effectiveness does not exceed 40 per cent,” he added. “All of this provides us a clear conclusion that the booster dose is of paramount importance in confronting this mutation that has spread around the world in a short span of time.”