NEJM publication: Our new research shows the need for regular Pfizer COVID-19 vaccine booster shots to maintain effectiveness against serious COVID-19 illness caused by Omicron BA.1/2 and BA.4/5

A quick look back: We first reported 70% Pfizer vaccine effectiveness against serious illness during South Africa's fourth wave

In February 2022, the New England Journal of Medicine (NEJM) published our correspondence sharing the first real-world Pfizer-BioNTech COVID-19 vaccine effectiveness data in South Africa, against early Omicron variants (predominantly BA.1 over the study period). At the time we found that two doses of this vaccine resulted in 70% effectiveness against serious COVID-19 illness (hospital admission) during the Omicron-driven (BA.1 and BA.2) fourth wave. While very good, this effectiveness was lower than the 93% effectiveness against the Delta variant, which we reported on in South Africa's third wave of infection (which took place in mid 2021). We concluded by suggesting that a booster dose of the Pfizer vaccine may balance out the reduction in effectiveness our results showed. We carried out this research with leading South African scientists.

We are now able to give updated, feedback on the protection and durability offered by two doses (original dosage regimen) and three doses (two doses with a booster dose) of the Pfizer COVID-19 vaccine as we now have access to data over a longer follow-up time. Our new data spans South Africa's fourth wave and more recent fifth wave of COVID-19.

New research published by the NEJM looks at Pfizer vaccine effectiveness over SA's fourth and fifth waves

On 14 September, the NEJM published (again as correspondence to the Editor) our new research - one of the first real-world studies in this area - on the effectiveness of the Pfizer-BioNTech COVID-19 vaccine against Omicron variants BA.1 and BA.2 and also Omicron sub lineages BA.4 and BA.5.

• This research, also a collaboration with leading South African scientists, is called "Effectiveness and Durability of the BNT162b2 Vaccine against Omicron Sublineages in South Africa." Read it here.

BA.1 and BA.2 drove South Africa's fourth wave of COVID-19 infection (15 November 2021 to 28 February 2022) and BA.4 and BA.5 drove the fifth wave (15 April to 24 June 2022 ).

The study analyses data from nearly 33 000 Discovery Health administered medical scheme members who were hospitalised between 15 November 2021 and 24 June 2022 and had a PCR test for COVID-19. We were then able to narrow this down to looking at two- and three-dose Pfizer vaccine effectiveness against serious illness in almost 6000 people who were hospitalised with COVID-19.

Our findings

• Two doses of the Pfizer-BioNTech COVID-19 vaccine proved 56.3% effective in protecting against hospitalisation in the fourth wave (BA.1 and BA.2 Omicron variants) and 47.4% effective in the fifth wave (BA.4 and BA.5 variants), three to four months after vaccination, declining from about 80% effectiveness in the first two to four weeks since receipt of the last vaccination dose.
• Having had two Pfizer doses plus a third (booster) dose maintained effectiveness against severe disease caused by all four sub lineage variants for one to two months more, but by three to four months after booster dose vaccination this effectiveness had dropped to 50% during the fourth wave (down from 56.3% at the height of vaccine effectiveness) and 46.8% in the fifth wave (down from 47.4% at the height of vaccine effectiveness).

Discussion and conclusion

"Having two or three doses of the Pfizer-BioNtech COVID-19 vaccine creates the desired result of protection from severe COVID-19 illness against Omicron's original and later sub lineage variants. However, this protection is short-term (likely sufficient to protect against hospitalisation during a single wave of infection) as we find a rapid waning in vaccine effectiveness three to four months after a second or third Pfizer dose," explains Collie.

"So, looking at the current climate in South Africa, to maintain vaccine effectiveness against serious illness caused by BA.4 and BA.5 (still dominant in South Africa), there's a need for regular Pfizer COVID-19 vaccine boosting, as often as four months after the last dose. Alternatively, available vaccines need to be adapted to better cater to circulating variants of concern to maintain longer-term protection."

"We are humbled and privileged to have had the opportunity to support such an important research study. This is work that's fully aligned to Discovery Health's core purpose to make people healthier and to enhance and protect their lives."

Acknowledgements

This research was authored by top South African scientists and members of the "Health Intelligence Unit" at Discovery Health:

1. Professor Glenda Gray, President of the South African Medical Research Council.
2. Professor Linda-Gail Bekker, Director of the Desmond Tutu HIV Centre at the Institute of Infectious Disease and Molecular Medicine at University of Cape Town; and Chief Executive Officer for Desmond Tutu Health Foundation.
3. Dr Lesley Bamford, Child Health Specialist at the National Department of Health.
4. And, Discovery Health's Shirley Collie (Chief Healthcare Analytics Actuary), Jiren Nayager (Actuarial Analyst) and Matthew Zylstra (Senior Actuary, Risk Intelligence).

Shirley Collie and the other members of Discovery Health's Health intelligence team would like to extend their sincere thanks to Prof. Gray, Prof. Bekker and Dr Bamford for their guidance, support and leadership in carrying out this research.

Interested in knowing more or reporting on these findings?

Please contact us on MEDIA_RELATIONS_TEAM@discovery.co.za to request any updated data available since publication and to obtain any further context required.

Did you find this post interesting?

Consider reading our related post, "Deep dive: Admission rates across South Africa's four COVID-19 waves confirm Omicron-driven fourth wave's lower severity" These dynamics are fed by Omicron's lowered pathogenicity, vaccination rates and population-wide seropositivity.

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