Thread by @ShabirMadh

South Africa on cusp of resurgence, after the high infection rate with Omicron- albeit massive decoupling of infections and severe disease materialising. Current resurgence likely due to sub-lineage of Omicron- BA4. What can we expect, now that >80% population have some immunity

Most of immunity in SA unfortunately resulted from infection (>80% infected since start of pandemic). In addition ~40% received at lease single dose Covid vaccine. Evidence indicates hybrid immunity protects as well as vaccine only induced immunity (rare in SA), if not better

In addition, infection only induced immunity shown to be more protective than 2 dose Pfizer only induced immunIty in Qatari study. That is not to say people should go out to be infected - as that comes at cost of suffering and loss of life/ which is NOT the case with vaccines.

Nevertheless, cannot dismiss impact infection induced immunity, that inadvertently evolved in SA despite restrictions, will have on trajectory of pandemic. Infection induced immunity induced depth of T cell responses that protect against severe disease even against variants

?expectations with BA4 ( and perhaps some other variant which evolves). Likely will experience many infections, more so in people not infected during omicron wave, but also some reinfections after Omicron if occurred sometime ago. Infections least likely if have hybrid immunity.

Can we prevent infections? Yes , if using right type mask (N95 type) and wearing it correctly, avoiding indoor poorly ventilated spaces. Needs to be considered for anyone at high risk of Covid- irrespective of vaccinated. But, little potential impact on resurgence in SA context

As was “successfully” done for Omicron wave in SA, when restrictions were pretty much abandoned, there was no overwhelming of health services as Omicron wave accounted for 5% of Covid deaths since start of pandemic - >90% in unvaccinated. With BA4, will likely be more decoupling

Health care facilities should, however, be prepared. The focus in SA context, unlike countries able to truly minimise infections en masse, is about minimising severe disease . Ongoing effort required to get beyond the 65% of older than 50 vaccinated to at least 90%.

Need to be cautious, but no need to panic as we live with the virus. Any pretence that we achieve much with regulations aimed at preventing infections is dismissive of what transpired in SA, and agnostic to the detrimental impact on SA which disproportionately affected the poor

Infections do result in risk of long Covid - although most data from when people were infected prior to developing immunity. Vaccine induced immunity reduce risk of long Covid, and expect the same with infection induced immunity. Viz. risk of long covid lower now in SA after Ix

Need to also start getting excess to Pfizer anti- viral, to help protect high risk groups after infection. Unfortunately, appears to be on same course as vaccines - unacceptable delayed access in low and middle income countries, while doses are hoarded in high income countries

Always, although unlikely, that new variant could evade T cell immunity that protects against severe Covid. In the unlikelihood of that occurring, we back at square one - as would make current immunity largely obsolete, taking us back to March 2020. Can rename Covid to Covid -22

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