Thread by @miamalan

BREAKING [Thread]: 1. SA’s first real-world data on #Pfizer’s #COVID19 jab’s protection @ #Omicron infection + hospitalisation via @Discovery_SA + @MRCza

Note: This is data from the 1st 3 weeks of the outbreak, so it might change - regard it as preliminary real-world data

2. What data are findings based on?
1. @Discovery_SA = SA’s largest health insurer (3.7 mil members)
2. They used 211,000 positive #COVID19 PCR tests of adults (18+)
3. 41% of 211,000 + tests = received 2 doses of #Pfizer

3. Here is how #Omicron has progressed in SA:
#Omicron = now 90% of #COVID infections in SA

4. How effective is #Pfizer’s jab @ hospitalisation due 2 #Omicron?
1. 2 doses of #Pfizer’s jab makes vaccinated people 70% less likely 2 get hospitalised vs. unvaccinated people
2. This = lower than 93% protection the jab gave in SA’s #Delta wave (93% = @Discovery_SA data)

5. Protection of 2 doses of #Pfizer @ hospital admission due to #Omicron is maintained across all ages (18-79 years), but slightly lower for older age groups:
18-29: 92%
30-39: 75%
40-49: 82%
50-59: 74%
60-69: 67%
70-79: 59%

6. Important to note that the lower protection (down from 93% to 70%) against hospitalisation because of #Omicron could be because older people were vaccinated first in SA, so there has been a longer period for vaccine-derived immunity to wane than with younger age groups

7. 70% protection for vaccinated people @ hospital admission = still a high level of protection. WHO regards a #COVID19 vaccine effective if it provides 50% protection: bit.ly/325K60Y

8. What about the risk of hospitalisation due to #Omicron infection compared to the variant (D614G) which dominated SA’s 1st #COVID wave?

Adults (18+) infected with #Omicron = 29% less likely to be hospitalised vs. infection with other variants

9. What are confounding factors for #Omicron real-life hospital admission data in SA?
High seroprevalence #SARS-CoV2 antibody levels in SA population (so antibodies due to previous #COVID19 infection) - in Gauteng = as high as 70% + of people

10. Hospital admissions (anecdotal data):
1. Most #Omicron admissions = unvaccinated people (16% of ICU admissions = vaccinated)
2. High % of incidental admissions (people going 2 hospital 4 things other than #COVID + test 4 admission + find out they have #COVID)

11. Out of hospital data (anecdotal):
1. @Discovery_SA is seeing milder illness with #Omicron (early data) with recoveries within 3 days
2. Higher reinfections (so people who've had #COVID19 get infected again) and breakthrough infections (vaccinated people getting infected)

12. #Omicron cases are growing much faster than during the #Delta wave, but hospitalisations slower. For the Omicron wave, SA has reached 60% of cases reached during the #Delta peak but we have reached only 20% of the hospital admissions of the Delta wave.

13. Children and #Omicron:
1. Main diagnoses 4 kids who get hospitalised = bronchiolitis and pneumonia, often with severe gastrointestinal symptoms + dehydration
2. Most kids = not hospitalised = mild symptoms (sore throat, nasal congestion, headache, fever, resolves in 3 days)

14.
1. Kids below 18 infected with #Omicron = 20% higher risk of admission 4 #COVID19 complications vs. 1st wave
2. This aligns with the 3rd #Delta wave (June-Sep 2021) when an increase in pediatric admissions (0-5 yrs) = also seen (so 4th wave risk = similar to 3rd wave risk)

15. To date, kids below 5 = higher admission risk than adults, but this could be driven by incidental admissions. This trend is starting to change: it looks like fewer children and more adults are starting to get admitted (@nicd_sa = similar findings).

https://twitter.com/miamalan/status/1469268446932344836

16. NB data to point out re children:
1. The risk of kids testing + for #COVID19 because of #Omicron = 51% lower compared to adults
2. @nicd_sa/@MRCza data from Tswhane show most kids = admitted 2 hospital = incidental admissions

https://twitter.com/miamalan/status/1467172016918773775

17. Vaccinated people = 33% less likely 2 get infected with #Omicron than unvaccinated people (this is a drop from 80% protection during the #Delta wave)

Here's how #Pfizer protection @ infection wanes 4 Omicron:
1. 2-4 wks after 2nd dose: 56%
2. 3-4 mnths after 2nd dose: 25%

18. What about the risk of reinfection?

1. People infected with #Delta = 40% relative risk of reinfection with #Omicron
2. People infected with Beta = 60% relative risk of infection with Omicron

19. More data on the reinfection risk with #Omicron:

@SACEMAdirector et al. in SA found the relative risk of reinfection with #Omicron for people who previously had #COVID and get exposed again = 3 times higher than for reinfection with #Delta/#Beta:

https://twitter.com/miamalan/status/1466769386849681410

20. Two shots of #Pfizer continues to provide good protection @ hospitalisation, but protection has dropped from 93% with #Delta to 70% with #Omicron.

21. The protection @ hospitalisation that 2 shots of #Pfizer provide @ #Omicron infection for different ages:
- Highest protection = 18-29 yrs
- Lowest protection in 70-79 yrs
(Could be because 70-79 = vaccinated before 18-29, so = been more time for 70-79's immunity 2 wane)

22. This graph shows that #Omicron infection is associated with a 29% lower risk of hospital admission for adults compared to the 1st wave, but children have a 20% higher admission risk (but as mentioned previously, looks like it's starting to change).

23. Although excess deaths were high for the week of 28 Nov, it's still much lower than in previous #COVID19 waves (this correlates with lower #Omicron death rate data in hospitals, but it's early times)

24. How did @Discovery_SA obtain #PCR test data?
1. Results from @LancetLab_ZA [private lab] (45%)
2. Gauteng test results 55%
3. Results from hospital patients 8%

25. Summary:
1. Vaccination continues to provide significant protection @ falling seriously ill with #COVID (although reduced to 70%)
2. High nrs of breakthrough infections in vaccinated people (protection @ infections reduced from 80% to 33%)
3. Reinfection risk = increased

Find the press release here: discovery-holdings-ltd.mynewsdesk.com/documents/pres…

Find the recording here: dsycloud.zoom.us/rec/share/F90e…

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