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How well is Pfizer’s Covid jab working in SA? We break down some of the data

Early data collected between May 17 and June 29 from Discovery Health’s members, shows both a lower rate of SARS-CoV-2 infection and Covid-related hospital admissions among members who had been vaccinated with one dose of Covid vaccine compared to non-vaccinated members. 

The Pfizer vaccine requires two shots, which are given 42 days apart in South Africa. Pfizer’s safety and efficacy trial showed that the jab was 95% efficacious in preventing Covid-19 of any severity in study participants who had not been infected with SARS-CoV-2 before vaccination. Further analysis found the vaccine was 100% efficacious in preventing participants from developing severe disease, as defined by the US government’s Centers for Disease Control. 

However, during the time that Discovery collected data on vaccinated members, three variants of the SARS-CoV-2 virus, which are all more transmissible than the original form of the virus against which Pfizer/BioNTech measured the efficacy of their vaccine, were circulating in South Africa. The Beta variant, first identified in South Africa in October, was dominant in the country, the Delta variant, first identified in India, was rapidly spreading in Kwazulu-Natal and Gauteng and the Alpha variant, first identified in the UK, was present in some provinces. 

The Pfizer/BiotNTech jab’s efficacy for two of these variants is lower than for the original form of the SARS-CoV-2 virus, because the variants are, to some extent, able to escape both natural immunity, as well as the immunity response induced by the jab. In the case of the Beta variant, studies have shown that this form of the virus can reduce the ability of the vaccine to neutralise SARS-CoV-2 up to tenfold, but the vaccine is still very effective in preventing severe disease caused by the Beta variant. For the Delta variant, data from cases in England has revealed that the variant reduces the efficacy of the Pfizer/BioNTech vaccine to prevent Covid-19 from 51% to 33% after one shot and 93% to 87.9% after two shots.

Data released by the Israeli government this week — the Pfizer/BioNTech vaccine has been rolled-out widely in Israel — shows that the jab provides 93% protection against serious illness and hospitalisation caused by the Delta variant. 

Because the data we collected for Discovery members is very early at this stage and is for the first 35 days of our vaccination programme, before second doses had began, we looked at the effect one dose of the vaccine 21 days after it had been administered to people of 60 years or older (because at the time, that group and healthcare workers were the only populations eligible for vaccination). 

Consequently, the data set we are drawing from is an early set of insights and was gathered for older vaccinated people only. 

Discovery’s analysis focused on data from 46 007 vaccinated Discovery Health members — all of them living in Gauteng — and studied how this group’s infections, hospitalisations and deaths compared to a matched clinical cohort of unvaccinated members. 

How did we obtain access to the data? 

Discovery Health receives all its clients’ pathology PCR Covid test results on a daily basis from the laboratories. We routinely pre-authorise funding for all in-hospital admissions. We also record all deaths of health policy holders, primarily through medical scheme policy withdrawal records. Access to this information empowers us to collect and analyse accurate data on confirmed SARS-CoV-2 infections (through PCR test results) and hospital admissions, as well as deaths within 21 days after members had been vaccinated with one dose of Pfizer/BioNTech. This represents a unique data source, in our view, and provides powerful insights into the vaccine effectiveness and other elements of the Covid-19 pandemic in South Africa. 

Our findings were that:

  • Within the vaccinated member group, 176 infections occurred and within the unvaccinated group 260 infections were recorded; 
  • For the vaccinated group there were 49 Covid-related hospital admissions and for the unvaccinated group 84 admissions; and
  • No deaths occurred in either group. 

After allowing for follow-up time differences between the vaccinated and unvaccinated groups, we noted the following:

  • A 47% lower rate of new SARS-CoV-2  infection in the vaccinated group compared to the unvaccinated group; 
  • No Covid-related deaths occurred in the vaccinated group, compared to one Covid-related death in the unvaccinated control group.

Our early data supports the results of studies that demonstrate the protective effect of Covid-19 vaccination. 

This reinforces the call to vaccinate as many members of our population as possible, importantly prioritising those who are most at risk of severe Covid-19 illness, such as people aged 60 and older. 

We are further encouraged to note that only 8 080 (5.7%) of a total of 141 646 vaccinated members of the medical scheme administered by Discovery Health, have submitted claims between 15 May 2021 and 29 June 2021 related to possible vaccination side effects after their first dose. These were primarily for over-the-counter pain, and fever-reducing medicines. To date, only one scheme member has required admission to hospital for a potential vaccine side effect — the member was coughing, had a temperature and was wheezing. 

It remains important to continue to monitor this data as it matures, particularly after the second dose of the regimen is administered — we will, therefore, continue to provide further insights from our 3.7-million administered medical scheme members’ vaccination experiences as these emerge. 

Meanwhile, and as our vaccine roll-out progresses, we simultaneously find ourselves in the grip of a rising third wave of SARS-CoV-2 infections in South Africa. All indications are that the country’s  third wave, driven by the significantly more transmissible Delta variant, is anticipated to have higher case loads than the first and second waves, simply by virtue of the higher volume of cases. At this stage, our data shows, there does not seem to be a higher admission rate during this wave.  

Gauteng health statistics show that hospital occupancy rates in both the public and private sectors are at more than 90%. Given that our data shows that on average there is a six-day lag between testing positive for SARS-CoV-2 and hospitalisation, the capacity of our country’s healthcare system to cope with the emerging load over the coming weeks is particularly concerning.

The evidence is conclusive that non-pharmaceutical interventions — such as remaining home as far as is feasible and, when out and about, ensuring mask wearing; hand hygiene; social distancing; and opting for outdoor or well-ventilated areas — work to slow down the spread of the virus. 

Our collective behaviour will determine the extent of person-to-person spread.

In the context of the third wave, it is also important to point out the following two critical facts:

Firstly, a previous SARS-CoV-2 infection does not necessarily imply enduring immunity against future infection. Our latest Discovery member data shows that individuals who recovered from Covid during wave two, have a 65% lower risk for reinfection than those who had never been infected. But, although this is a significantly lower risk, it is not 100%, and the risk of reinfection remains. Current data suggests that people who had Covid caused by the Beta variant and, therefore, developed natural immunity, can potentially get reinfected with the Delta variant.  

It is also entirely possible to contract SARS-CoV-2 after being vaccinated, because no vaccine is 100% effective in preventing infection. For as long as we still have a very low proportion of the population covered through vaccination, and there are many potentially infectious people in communities, vaccinated individuals must still take all the necessary precautions, such as social distancing and mask-wearing, to protect themselves against infection.

Furthermore, every country faces the ongoing risk that new Covid-19 viral variants will emerge, as has happened in South Africa. The more the virus spreads, the greater the risk of the emergence of new variants, emphasising the need to slow the spread of the disease as much as possible. 

By July 8, Discovery had administered 110 617 vaccine doses at seven Discovery sites as part of the government’s national vaccine roll-out programme.      

Considering the strong global evidence about the protective effects of vaccines from countries in which vaccination is advanced, and taking into account the favourable early data we are seeing from Discovery Health, it is critical that we accelerate the pace of the national vaccine roll-out to reach as much of the population as we can and, hopefully, all willing adults by the end of the year. 

Ryan Noach is the chief executive of Discovery Health.

This story was produced by the Bhekisisa Centre for Health Journalism. Sign up for the newsletter.

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Ryan Noach
Ryan Noach is the chief executive of Discovery Health.

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