Will you need a second Covid vaccine booster shot?

The second booster shot (also called a fourth dose) against coronavirus may not come soon as the government studies different local and international scenarios to determine whether it will be necessary. 

Although some countries in the west are administering the shot to some target populations, Dr Willis Akhwale, chairman of the National Covid-19 Vaccines Taskforce, said the Health ministry cannot duplicate everything to justify the use of the fourth dose. 

“We do not copy everything the world is doing. We generate our own data and compare it with international information, which then informs our decisions,” said Dr Akhwale. 

In this case, he explained that the ministry will be considering three scenarios that will inform its decision to onboard a fourth shot or not. 

“One of the things we will be looking at is the number of people infected with Covid-19 and hospitalised after receiving the third dose,” he noted.

The ministry in partnership with the Center For Epidemiological Modelling and Analysis will also be comparing the status of vaccination against coverage across counties to monitor how devolved units with high vaccination coverage like Nairobi and Nyeri (43 and 44 per cent coverage respectively) fair compared to those with low coverage like Bomet (10 per cent) and Wajir (7.2 per cent).

“Finally, we will look at antibody levels and how they wane over time. These data will inform our decision,” said Dr Akhwale.  Currently, there is no convincing data that offering people a fourth dose is effective in providing further protection against Omicron and other Covid-19 variants. 

Dr Catherine Kyobutungi, an epidemiologist, explained that available data on the effectiveness of the fourth dose so far “is not convincing.” And if the data was there, she said she would only advocate for targeted third or fourth booster doses as a way of avoiding waste.

“The primary objective should be higher coverage of the whole population as fast as possible. Boosters should be secondary,” she said.

Some countries have begun offering people the fourth jab as a way of providing further protection against omicron infections, which have been found to have some level of immune escape against vaccine-derived immunity.

In early January, Israel became the first country to start administering a second booster, or fourth shot, to those aged over 60. In the US, the centers for disease control and prevention recently encouraged people with weakened immune systems to come forward sooner for additional coronavirus shots.

Meanwhile, the UK has said boosters are providing good levels of protection and there is no need for a second booster shot at the moment but that officials will review data as it evolves. Most countries offering a second booster shot are prioritising people with weak immune systems due to pre-existing medical conditions.

The rationale for these policies is supported by a range of evidence, including from the UK-based Octave study, which found that four in 10 people who were clinically vulnerable generated lower concentrations of antibodies than healthy recipients after two doses of a Covid-19 vaccine.

A preliminary study in Israel found that a fourth shot of the Covid-19 vaccine is not enough to prevent Omicron infections.

Although a fourth shot of the Covid-19 vaccine boosts antibodies to even higher levels than the third jab, it is “not good enough” to completely protect against infection from the omicron variant, Prof Gili Regev-Yochay, the director of Sheba Medical Center’s infectious disease unit and a lead researcher on the study said, as reported by the Times of Israel.

European Union regulators warned that frequent Covid-19 booster shots could adversely affect the immune response and may not be feasible. Repeat booster doses every four months could eventually weaken the immune response and tire out people, according to the European Medicines Agency (EMA).

Instead, the agency said that countries should leave more time between booster programes and tie them to the onset of the cold season in each hemisphere, using the blueprint set out by influenza vaccination strategies.

[email protected]