Thread by @celinegounder

1/ When will the pandemic be over? I talked to @alexismadrigal about it.

https://twitter.com/alexismadrigal/status/1364370411551531012

2/ The emergency won't be over until most of the elderly and those with chronic medical conditions--who are at the highest risk for severe disease, hospitalization, and death--have been vaccinated.

3/ The elderly population skews whiter. It's essential that we also get people with chronic medical conditions vaccinated, too, as this will capture most of the high-risk persons of color, who've been hit so hard by this pandemic.

4/ We should have enough vaccine supply for every American who wants to get vaccinated to do so by the end of July, if not sooner. That's different, of course, from shots in arms.

5/ I can't tell you exactly what proportion of the population we need to vaccinate to get to herd immunity because the emergence of variants that are more infectious will raise that threshold. In addition, it depends on how much vaccination prevents transmission.

6/ If transmission is only partially reduced, then you'd need a higher level of vaccination coverage. If transmission is completely blocked, then you wouldn't need as high a level of vaccination coverage. Our best guess right now is around 75-85% to hit herd immunity.

7/ But what makes our current situation an emergency is that we are still seeing about 2000 deaths per day (down from about 4000 deaths per day following the winter holidays), on par with March/April of last year.

8/ Hospitals and healthcare workers are still stretched too thin in some places and don't have enough personal protective equipment, and many high-risk workplaces (e.g. meatpacking, food processing, jails, and prisons) remain high-risk for transmission.

9/ Assuming the vaccines continue to protect against emerging variants, once we've vaccinated most of the elderly and those with chronic medical conditions (~130M people, or over a third of the U.S. population), our hospitalizations and deaths should plummet.

10/ But to vaccinate everyone with chronic medical conditions, we're going to prove ourselves trustworthy to communities of color. Trusted messengers are part of the solution, but that's not enough.

11/ We should also be vaccinating people in high-risk workplaces (e.g. meatpacking, food processing, jails/prisons) and improving administrative infection controls (e.g. screening/testing), environmental infection controls (e.g. ventilation), ...

12/ ...and providing appropriate personal protective equipment (e.g. N95 masks or equivalent) in these especially high-risk settings (meatpacking, food processing, jails/prisons).

13/ Meatpacking & food processing plants and prisons are major employers in many rural towns across the country. An outbreak in one of these facilities doesn't just affect the people working/incarcerated there. It can be devastating to the entire community.

14/ These rural communities also don't have the same health care capacity to cope with a spike in cases.

15/ Once the emergency is over, then what?
We need to strengthen public health:
- hire many more public health and community health workers
- strengthen public health bioinformatics systems
- strengthen public health lab capacity

16/ We need to scale up genomic surveillance. The CDC has done this since Biden took office, but we need to go even bigger. We need to know what new variants are emerging, what might be driving their emergence, and to characterize those new variants.

17/ Are these new variants more infectious? Why? Are they more virulent? Why? Do they evade our natural or vaccine-induced immune responses? Why?

18/ We need to be developing multivalent vaccines, which protect against the original strains of SARS-CoV-2 as well as emerging variants.

19/ We don't yet know if we'll need a one-time revaccination for emerging variants or whether we'll need an updated vaccine every couple years.

20/ It's likely that there will be much more viral heterogeneity in the early years after the virus has jumped into humans, and that the virus will stabilize over time.

21/ We need to be developing more drugs to prevent severe COVID & to treat COVID. These drugs need to be affordable & deliverable at scale. People will be getting sick & hospitalized with COVID for years to come, so we need better tools at our disposal. washingtonpost.com/opinions/2021/…

22/ And then what? Could we hope for #ZeroCOVID one day? In other words, elimination of SARS-CoV-2 transmission?

23/ Once the vast majority of people have been vaccinated, COVID vaccination will likely become a childhood vaccination (assuming we don't need frequent boosters for variant strains). Newborns will constitute the majority of persons entering the population who are susceptible.

24/ Other susceptible persons will include those with waning immunity (in particular the elderly) and travelers and immigrants from overseas.

25/ There are precedents for restricting travel or immigration on the basis of vaccination status (e.g. Yellow Fever) or screening (e.g. tuberculosis). We may find ourselves eventually, once the vaccine is widely available, requiring proof of COVID vaccination prior to travel.

26/ But I think it would be difficult to do this until everyone, at least in this country, who wants to get vaccinated can be.

27/ In an ideal world, we'd try to go for elimination of SARS-CoV-2 in the U.S., but this would require very high levels of vaccination coverage. Elimination (at least for measles) would mean the absence of endemic transmission (community spread) in the country for 12+ months.

28/ This means that the COVID cases we'd see would be from reimportations into the country, not from community transmission. We've done this with measles, another highly transmissible, airborne infection.

29/ But measles doesn't mutate in such a way that we need to revaccinate periodically. We may need to revaccinate for COVID every couple years. Realistically, I think SARS-CoV-2 will likely become endemic in much of the world. nature.com/articles/d4158…

30/ When will life return to normal? That depends on what "normal" is." Back to the way things were? They may never. We may have a "new normal" in which we don't shake hands anymore and wear masks in the winter months, as they do in East Asia.

31/ We might change how we ventilate or humidify indoor spaces. Many older buildings have steam radiators that work too well. This is the result of the Fresh Air Movement following the 1918 influenza pandemic.

32/ The idea was to make it so hot inside that people would open their windows, even in the winter, improving indoor ventilation. npr.org/2020/12/10/945…

33/ Kids can already go back safely to in-person learning in much of the country so long as schools are given the resources necessary for everyone to mask and abide by other CDC guidance. cdc.gov/coronavirus/20…

34/ The threshold for school reopening/closing should be transmission in the schools, not broader community transmission, which may be higher than in the schools. The past year has shown that schools are among the safest in-person workplaces.

35/ We also need to acknowledge that new infections are emerging with greater frequency--driven by climate change, environmental degradation, deforestation, and overpopulation--in other words anything that brings people in closer contact with wildlife habitats.

36/ And that means that we really do need to adopt a new normal to better insulate ourselves against the next SARS-CoV-2. This won't be the last pandemic. Not by a long shot. //