What do I mean when I say “endemic” transmission? Roughly, the use of this term falls into one of two camps: “self-sustaining transmission” or “regular and predictable transmission”. The former is the more public health definition, the latter is the more math definition. A 🧵 In the first case, “endemic transmission” or an “endemic disease” means that it is persistent and sustained without the need for continual reintroduction from outside a given population. It’s like an antonym of “eliminated” 2/

I’ve seen a flurry of discussion about metrics for COVID in the Omicron wave: cases, hospitalizations, deaths. The first is clearcut but a poorer indicator of societal impact. The latter two unfortunately indeterminate. Cause attribution has always been challenging a 🧵 1/ TL;DR — Counting is hard. Counting is boring. Counting is terribly important. The thing we’re counting should change over time to reflect our changing ability to measure and the goals we’re trying to achieve. (References at the end) 2/

Great to see a line waiting for the Whit Building testing center to open at 9. Penn Staters at UP get your free rapid test before noon and head into the New Year with confidence! Line is moving quick! The team here has been killing it this week!

There’s a lot to unpack here. One thing I’ve heard from clinicians throughout the pandemic is “don’t order at test you won’t act on”. Here that is married with “don’t order a test that you can’t offer”. There is a lot here that makes sense to me, even if I’m not 100% on board 1/ For background, I’ve spent years working on problems in low & middle income countries that need empirical decision points, e.g: When to
1. introduce rubella vaccine into a routine schedule
2. stop doing measles vaccine campaigns
3. stop external funding for vaccination 2/

PSA: Penn Staters in State College - the White Building testing center is open 9-noon on NYE. If you’re in line by noon you get a test. Please get tested ahead of NYE and bowl game activities and encourage others to do so as well. Lucy thanks you for it! She has also asked if we can come visit folks in line … we’re considering it

If anyone in the range of this tweet is doing the political calculus on whether they can take the risk and only call for a vaccine mandate if it gets bad enough to generate consensus … I’m here to tell you it won’t work 🧵 I’ve worked on outbreak response vaccination for a while and been a strong advocate for it in settings where it will help. My work (among many others) was cited in the 2005 policy change by WHO to recommend outbreak response vaccination in during measles outbreaks. 2/

Testing, like vaccination, is a demonstrably valuable tool for limiting outbreaks. However, tests without a well designed plan for implementation and operations is much less valuable.
apnews.com/article/health… The Acting Secretary of Health knows this - “We’re going to hear the same arguments about this that we heard about masking and vaccinations,” he said. “Superintendents and school board members are right back in the same hot seat as they were a year ago.”

xcellent reporting by @amymaxmen as always. My take is that too often we focus on adding bureaucracy to prepare for pandemics rather than filling the gaps in existing systems 🧵

Has COVID taught us anything about pandemic preparedness? nature.com/articles/d4158… The thesis of this piece — better prepare to respond to spillover than predict it — is spot on and should be taken further. The bulk of investment should address current threats. Pandemic preparedness must be built on a system of universal care and routine public health 2/

At a school board meeting last night a member of the public claimed that it was unfair to compare the COVID vaccine to the polio vaccine because “polio was a disease of children and COVID isn’t” and “the risk of COVID is super low” … this was incorrect on two fronts 1/ First — polio was endemic when the vaccine was introduced. That means that most adults had immunity from prior exposure as children and so, when the vaccine was introduced, the population of people at risk were disproportionately children who hadn't yet been exposed 2/

Another (late) take on CDC messaging — the relaxation of restrictions for fully vaccinated persons is about *individual* behavior and risk. Many institutions are grappling with how to set logically consistent policy that address *collective* risk 1/ Universities, businesses, and large institutions do have a logically consistent argument for more restrictive policies that minimize the risks to at-risk groups, marginalized populations, and operational disruptions consistent with institutional goals 2/

On a call this AM, someone in university operations said “what does 70% coverage even mean? Is that 70% of the whole university? 70% of each unit?” … and friends, I felt the last ten years of my research just perk right up. Just because it’s a great opportunity to promote the work of others .. @sakitakahashi1 did great initial work on estimating sub-national variation in measles coverage using survey data nature.com/articles/ncomm…

Since I’ve been asked about it a bunch today, here’s my take. Herd immunity is a journey not a destination. Asking “if we’ll get there” is just the wrong question, both technically and operationally 1/ Technically, “herd immunity” describes the incremental reduction or risk to everyone of being in a population where an increasing number of people are immune. That journey starts with the first immune person … it’s just not much of an additional push then 2/

My MSC (wildlife) advisor wrote a paper asking “is over abundance a conservation concern?”, basically making the case for preparing way in advance for the success of interventions. We’re seeing the failure to do think ahead manifest in misguided COVID policies now 1/ We knew vaccines were coming, we knew lack of documentation would create incentives for cheating. People claiming immunity to avoid masking/testing/distancing. Yet we’re still seeing ham handed messaging & rules that put the cost of compliance on private citizens 2/

Only a fool would wager on the herd immunity threshold for COVID after the year we’ve had … but I would wager this — 10 years from now we will still be debating the HIT for SARS-CoV-2 🧵1/

Five reasons why COVID herd immunity is probably impossible nature.com/articles/d4158… The HIT is a magnificent, elegant theoretical result. It is very powerful for planning — it is the reason that we can make plans now to open schools and businesses in later even if we won’t have 100% of the population immune (vaccine or exposure) 2/

Because it’s 2021 and we have to say the quiet parts out loud:
Vaccinated individuals must still wear masks, distance, and be treated exactly the same as non-vaccinated individuals. This isn’t just about immunity … 1/ The risks of creating a vaccinated/unvaccinated class system are:
1. It would certainly exacerbate existing inequities in access to services
2. It will create incentives for cheating and forgery of vaccine documents
3. It will put the onus on citizens to police that system 2/

It’s interesting to note that vaccinating in the face of an ongoing outbreak doesn’t have a terribly long history, even for a disease like measles, where we’ve had a highly effective vaccine for decades. It’s worth reviewing in the light of the rollout of COVID vaccine 1/ As recently as 2005, vaccination in response to measles outbreaks as contra-indicated by WHO 2/

who.int/csr/resources/…

IHME has produced some excellent work (I count its staff members among my collaborators and friends), but also a variety of challenging conflicts of interest. The 2018 MOU with WHO is particularly so 1/

https://twitter.com/talexperkins/status/1334685889419677696

The WHO reliance on IHME for burden of disease metrics creates a too-big-to-fail problem that also disincentivizes investment in in-country capacity. LMIC researchers will struggle to convince WHO that their efforts stand up to the IHME juggernaut 2/

I’ve been thinking about vaccination cards in the US a lot and am struggling to figure out what side to fall on. Cards are a huge part of monitoring and communication in LICs. Without them we’re really in a fog about vaccination coverage 1/

https://twitter.com/edfelten/status/1334498173423919111

We haven’t got recent experience in the US, so this would be a new strategy and could go awry, leading to stigma and adverse consequences 2/

Hey PSU folks — It’s come to my attention that there is a rumor circulating that I have tested positive for SARS-CoV-2 and am ill. Both are false. It is heartwarming to receive the well-wishes but I am fine 1/ It is also a moment to reflect on the fact that testing positive for a communicable infectious disease is not a condemnation of the individual. If anything, it reflects a failure of the public health infrastructure to prevent that outcome 2/

A thing won't save us, systems will - a thread co-sponsored by @nitanother : A collective 2.5 decades of studying measles in LMICs has shown us that individual things (vaccines/tests/drones) are not sufficient to eradicate a virus nor provide for the health of populations 1/ Measles has had a highly effective vaccine for over 50 years; has had effective serological tests (with a meaningful correlate of immunity) for decades, but that has not been enough to eliminate a virus that kills 100s of children a day worldwide 2/