Hard to deny that travel bans are now a key tool in the pandemic prevention toolbox. Fascinating to see how #COVID19 upended prior global health conventional wisdom about travel bans for epidemics and pandemics
Policies have evolved alongside the pandemic. In Jan @WHO recommended against travel restrictions when it declared coronavirus a public health emergency of international concern who.int/news-room/deta…
In Feb/Mar, WHO advise against the "application of travel or trade restrictions to countries experiencing COVID-19 outbreaks” and recommended “health measures be implemented in ways that minimize unnecessary interference w international traffic and trade”
WHO’s recommendations were in line with the previous consensus among public health experts that bans do more harm than good, and with prevailing interpretations of the International Health Regulations
For example, an editorial in late Feb stated that travel restrictions against China during COVID-19 violated international law, and “evidence belies the claim that illegal travel restrictions make countries safer” thelancet.com/journals/lance…
Even so WHO officials still recommended caution at that time: “restrictions must be based on a careful risk assessment, be proportionate to the public health risk, be short in duration, and be reconsidered regularly” thelancet.com/journals/lance…
However, travel bans were widespread already by then. 100% of countries had travel restrictions in place and 72% of countries had “placed a complete stop on international tourism” by April unwto.org/news/covid-19-…
Travel bans have been part of the success in countries suppressing the virus. Here is New Zealand’s Jacinda Ardern announcing "far-reaching and unprecedented" restrictions and touting the “toughest border restrictions of any country in the world” in March. abc.net.au/news/2020-03-1…
Studies show travel restrictions can reduce cross-border spread. Research from Australia: “Travel restrictions were highly effective for containing the COVID-19 epidemic in Australia during the epidemic peak in China and averted a much larger epidemic” academic.oup.com/jtm/article/do…
Another study: “travel restrictions…may decrease the rate of case exportations if enacted during the early stages of the epidemic… This obstruction of importation events will be critical to preparing an effective public health response” pnas.org/content/117/13…
But not all travel bans are created equal. Bans on travel from China early in the pandemic, were mostly too little too late and, at most, only delayed exportation of the virus into other countries. science.sciencemag.org/content/368/64…
Supporting this notion, an analysis of countries with and without early bans on travel from China found no association with countries’ subsequent outbreak size and timing. thinkglobalhealth.org/article/tracki…
Travel bans implemented haphazardly and/or incompletely offer little prevention value. The March ban on Europeans entering the US for example, did not help and might have made things worse washingtonpost.com/world/national…
If a country already has widespread community transmission, the relative importance and effectiveness is reduced. The risk from imported cases can become dwarfed by the risk from domestic transmission.
Because the pandemic is a dynamic situation, countries can be “net importers” or “net exporters” of disease at different times as they successfully or unsuccessfully suppress the virus. So, the relative effectiveness of travel bans can shift.
Since the April peak the has been a slow easing of travel restrictions. In July 40% of countries worldwide eased restrictions. However, over half of countries have kept their borders completely closed to tourism unwto.org/news/tourism-r…
Particularly in countries with low levels of transmission, travel bans remain in place to help prevent further surges or “second waves” of disease driven by imports.
According to @IATA there are only a few countries that *do not* currently place bans on international passenger arrivals, such as Brazil, Egypt, Mexico, Serbia, Tanzania, and Ukraine
So there is a complex interplay between a shifting epidemiological picture across countries, and differences in effectiveness of policies as implemented by countries. Raises broader questions about international cooperation and tourism in a world where many borders are closed
For example, with the epidemic in the US out of control at the moment, Americans are currently blocked from entering most countries around the world at the moment. cnn.com/travel/article…
For its part, WHO released new guidelines a few days ago, providing recommendations on how countries could ease travel restrictions safely: “gradual lifting of travel measures…should be based on a thorough risk assessment… who.int/news-room/arti…
“…taking into account country context the local epidemiology and transmission patterns, the national health and social measures to control the outbreak, and the capacities of health systems in both departure and destination countries”
Seems like a fruitful area for more study as travel circumstances are changing. Under what conditions do travel bans make sense? What are the effects of imposing/relaxing bans?

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More from @joshmich

19 Jan
30% of Israel's population has received at least 1 dose of Covid-19 vaccine, but no indications yet that case numbers are coming down there (chart).

A few reasons why this might be:

1) Cases reported now were infected 7+ days ago, when vaccinations were lower Image
2) Less than 500,000 (out of ~2.7 M vaccinated) have so far received a 2nd dose. A single dose is "less effective than we hoped" in providing protection, according to Israeli health leaders.
3) Israel has vaccinated by age, starting with older persons, vaccinating to date:
80% of 70+
68% of 60-69
50% of 50-59
28% 40-49

Older ages are protected from severe disease, but younger ages typically contribute most to transmission
Read 6 tweets
9 Jan
Beyond the scientific and epidemiological reasons to doubt the lab escape theory of pandemic origin, let’s not forget that no US or allied intelligence has emerged with even a whiff of evidence that a lab was the origin by accident or intention.
To believe the lab escape theory you also have to believe the Chinese have mounted a successful, extended campaign to eliminate incriminating evidence and muzzle officials and scientists who knew or might have suspected it came from a lab.
It’s a pretty big secret to hold on to, especially for a sizeable group of people that includes an international network of scientists, other workers, and families -- many of whom are not exactly in the secrecy business.
Read 17 tweets
1 Jan
That the US might adopt a 1 dose regimen or significantly delayed 2nd dose for vaccines already authorized seems more fanciful thought experiment than tractable policy. Pretty much all institutions and incentives are lined up against such a change and not without reason.
Current vaccines are authorized via EUAs from FDA, which both clearly state terms of use including a two-dose regimen. Moderna’s EUA says the vaccine is “administered as a series of two doses 1 month apart…”
“…Individuals who have received one dose of Moderna COVID-19 Vaccine should receive a second dose of Moderna COVID-19 Vaccine to complete the vaccination series.”
Read 20 tweets
31 Dec 20
CDC now provides more data on vaccine distribution and administration by state, agency, etc. Worth a look and a bookmark.

A few things that jumped out to me, in a short thread.

2.17 million doses distributed through the federal pharmacy partnership prgm for long-term care, but only 167,149, or 7.8%, administered. This is the phase 1a component that needs to make up the most ground.

If this program were a state, it would easily be the worst performer.
States/jurisdictions' overall progress in administering the vaccines they have received continues to vary widely.

DC has administered over 50% of its vaccines on hand, while Kansas has administered just over 10%.
Read 6 tweets
30 Dec 20
Worth noting that Kathleen Hicks, President-elect Biden's pick for the number 2 spot at the Pentagon, would be that unusual senior defense official with some background in global health, as it relates to national security.
She's co-authored reports on the Department of Defense and global health, such as this one from 2009
From that report: If "virulent diseases can destabilize economies and entire political systems, then it is in the national security interest of the US to address the causes of diseases and develop effective systems to detect and contain them."
Read 6 tweets
22 Dec 20
You may have seen CDC reporting 4.6 million doses of #COVID19 vaccine have been distributed & 614,117 administered. Why the huge gap between doses distributed vs administered numbers? (short thread)
Some of the gap is from reporting lag: it can take up to 3 days for providers distributing the vaccine to report to state/local health officials, and additional time for officials to report to CDC
Also, doses distributed to states have been held for use in long-term care facilities via the federal pharmacy partnership, which is only now starting to ramp up. Its goal is to reach 4.5 million residents and staff at 55,000 nursing homes nationwide
Read 8 tweets

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