- A third booster dose of Pfizer's vaccine has been approved for use in SA.
- Only those who received the initial two doses are eligible to receive an additional dose.
- The latest findings by Pfizer suggest that a third shot provides good protection against Omicron.
A third (booster) dose of the Pfizer-BioNTech Covid-19 vaccine has been approved for use in adults, the South African Health Products Regulatory Authority (Sahpra) said on Wednesday.
The option will be available for those who received the two-dose vaccine, but not for adults who received the single-dose Johnson & Johnson vaccine.
The regulator added that a third dose of the vaccine will also be available to children (aged 12–17 years) with immunocompromised conditions.
The approval came hours after the announcement of the results of a preliminary study assessing the impact of a third dose of the vaccine against the Omicron variant.
According to a statement by Pfizer, laboratory studies suggest that three doses of their vaccine neutralise the recently identified variant of concern.
Interval between second and third dose
Adults who received the two-dose vaccine will be eligible to receive their third dose at least six months after their second dose.
South Africa started vaccinating children aged 12–17 years in October. As of 9 December, the department of health opened up vaccinations for this group to receive their second dose – previously, only one dose was offered.
A third dose has been approved for children in this age group, as well as immunocompromised adults, and should be administered at least 28 days after the second dose, Sahpra said.
When can you get it?
In a statement on Thursday, the department said that Sahpra's approval of the third dose means that the Vaccine Ministerial Advisory Committee can now advise the minister of health, Joe Phaahla, on when to proceed with the booster shot.
"The Department will tomorrow [Friday], make a formal announcement and explanation on any changes to the schedule for administrations of vaccination doses," it said.
No decision on mixing and matching
"The data provided only dealt with the situation of homologous boosting, where the third dose is of the same vaccine as the initial course (in this case, two doses)," Sahpra said.
The regulator said that it was aware of “mix-and-match” dosing, where a single dose of J&J can be topped up with a dose of Pfizer’s vaccine, for example. This option is currently being offered in other countries.
While Sahpra has not approved this approach in SA, it invited the submission of supportive data in this regard.
Pfizer's study on Omicron
As the country braces itself for a fourth wave, it is believed that the Omicron variant may be driving the increase in cases.
According to the study, a third dose of the mRNA vaccine increased antibody protection against Omicron 25-fold compared with its two doses.
This additional shot had an effect on the new variant that was comparable with the 95% protection provided by two doses against the "original" virus that first circulated globally, the company said.
Two doses protective, third dose better
It added that the two doses may still protect against severe Covid disease caused by Omicron – a point local experts have stressed for the past two weeks.
However, Albert Bourla, chairman and CEO of Pfizer, said: “Although two doses of the vaccine may still offer protection against severe disease caused by the Omicron strain, it’s clear from these preliminary data that protection is improved with a third dose of our vaccine.”
It remains to be seen how the additional dose performs in a real-world setting against the Omicron variant.
Other countries offering boosters
Several other studies have demonstrated the benefit of an additional dose of the Covid vaccines in enhancing the immune protection against infection and severe Covid-19.
As a result, more than 100 countries have started rolling out booster shots, including America, Austria, Germany, Sweden, Britain, and Spain.
There has been disagreement among scientists and public health officials regarding offering additional doses as the World Health Organisation requested that the most vulnerable people worldwide should be fully vaccinated first.
But the emergence of Omicron has prompted a reconsideration.
Pfizer and BioNTech are also developing a variant-specific vaccine for Omicron.
Ugur Sahin, CEO and co-founder of BioNTech, said: “We continue to work on an adapted vaccine which, we believe, will help to induce a high level of protection against Omicron-induced Covid-19 disease as well as a prolonged protection compared with the current vaccine.”
This week, South African researchers posted the early results of their study which indicated that Omicron could partially evade protection provided by two doses of Pfizer’s vaccine, Health24 reported.
However, vaccinated individuals with prior infection were found to have stronger protection against the variant. The study was led by Dr Alex Sigal, a virologist at the Africa Health Research Institute.