Greetings again MCG,
The medical evidence document has been updated again, and can be accessed from the same link here: https://www.iata.org/globalassets/iata/programs/covid/restart/covid-public-health-meausures-evidence-doc.pdf
One of the areas which has been updated relates to vaccination preventing transmission.
It will continue to be updated, but new versions will be at the same above link (complete with spelling mistake).
Vaccination and Transmission
There is a small but growing list of papers suggesting that vaccination effectively reduces asymptomatic infections; I have sent you some of these previously, particularly Haas et al below. In addition there are a few which have looked at regularly tested healthcare workers (Keehner et al, Swift et al, Tang et al, Weekes et al) or patients screened pre-procedure (Tande et al) and shown that vaccination is highly effective at reducing asymptomatic infection which implies that the chance of onward transmission is reduced.
An even smaller number of papers look directly at onward transmission being prevented by vaccination. One of these is Harris et al from Public Health England, looking at the families of healthcare workers. The infection rate in the (unvaccinated) family members of those who had been vaccinated (with either Pfizer or AstraZeneca) was around 40-50% less. https://khub.net/documents/135939561/390853656/Impact+of+vaccination+on+household+transmission+of+SARS-COV-2+in+England.pdf/35bf4bb1-6ade-d3eb-a39e-9c9b25a8122a?t=1619601878136
Another study taking a similar approach in Scotland (Shah et al, https://doi.org/10.1101/2021.03.11.21253275 ) had similar findings. And I previously forwarded the study by Pritchard et al. from Oxford showing high effectiveness in preventing symptomatic infections but less (about 50%) in preventing asymptomatic ones.
Other studies have looked at the actual infection rate following vaccination compared with what would be predicted, in communities (Milman et al https://doi.org/10.1101/2021.03.26.21254394 ) or elderly care homes (De Salazar et al, https://doi.org/10.1101/2021.04.08.21255108 Monge https://www.medrxiv.org/content/10.1101/2021.04.08.21255055v2 ).
Others have demonstrated reduced viral load in vaccinated people who are subsequently infected (Levine-Teifenbrun et al https://doi.org/10.1038/s41591-021-01316-7 ) suggesting lower risk of transmission.
A study from UCLA looked at mucosal antibodies in the upper respiratory tract (measuring oral fluid but with a reference check against nasal swabs), and found that the oral fluid IgG levels were high in 100% of participants from 15 days after vaccination (Moderna). This in encouraging in terms of low chance of transmission following vaccination.
Mades A, Chellamathu P, Lopez L, et al. Detection of persistent SARS-CoV-2 IgG antibodies in oral mucosal fluid and 2 upper respiratory tract specimens following COVID-19 mRNA vaccination. medRxiv [Pre-print] [Posted 2021, May 7]. Available from: https://www.medrxiv.org/content/10.1101/2021.05.06.21256403v1.full.pdf
Reinfection (being infected twice with SARS-CoV-2) is addressed in this peer-reviewed study, and was identified in 0.7% of patients, on average around 4 months apart. In general, reinfection appeared to have less severe clinical manifestations than the primary infection. There were 2 deaths (3.2%) associated with reinfection. (Qureshi et al https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab345/6251701 )
We continue to watch the available information on this question, and a CAPSCA sub-group is tasked with evaluating the literature.
A reminder also that ECDC has produced guidance on what restrictions could be relaxed for the fully vaccinated:
They include that “Requirements for testing and quarantine of travellers (if implemented) and regular testing at workplaces can be waived or modified for fully vaccinated individuals as long as there is no or very low level circulation of immune escape variants (in the community in the country of origin, in the case of travellers).”
A different scientific point - an article shows that IgA in the upper respiratory mucosa is important in the early immune response - Sterlin et al
Variants and Vaccines
The B.1.617 circulating widely in India has been classified in both UK and US as a variant of concern, on the basis of increased transmissibility – and WHO has now followed also classifying it as a VOC. There are three subvariants. A pre-print study shows reduced, but still reasonably high, efficacy of the mRNA vaccines against the sub-variant B.1.617.1 of it (there are two other sub-variants). Edara et al: https://doi.org/10.1101/2021.05.09.443299
The ECDC has posted a threat assessment regarding these variants, which it still classifies as a variant of interest, here: https://www.ecdc.europa.eu/en/publications-data/threat-assessment-emergence-sars-cov-2-b1617-variants
A meta-analysis has been published (as a pre-print) of rates of the rare Vaccine Induced Immune Thrombocytic Thrombocytopenia (VITT), the rare blood clot side effect, with data from 10 countries. Overall risk is 1 in 139,000; for age 65 and over, about 1 in 1,000,000; for age under 55, between 1 in 20,000 to 60,000.
The Pfizer vaccine has had its approval extended to include the 12-15 year age group by the US FDA (and also the Australian TGA).
Further detail on the CDC self-tests mentioned below:
International air passengers traveling to the United States can use a self-test that meets the following criteria:
The test must be a SARS-CoV-2 viral test (nucleic acid amplification test [NAAT] or antigen test) with Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA).
The testing procedure must include a telehealth service affiliated with the manufacturer of the test that provides real-time supervision remotely through an audio and video connection. Some FDA-authorized self-tests that include a telehealth service may require a prescription.
The telehealth provider must confirm the person’s identity, observe the specimen collection and testing procedures, confirm the test result, and issue a report that meets the requirements of CDC’s Order (see “What information must be included in the test result?” below).
Airlines and other aircraft operators must be able to review and confirm the person’s identity and the test result details. The passenger must also be able to present the documentation of test results to U.S. officials at the port of entry and local/state health departments, if requested.
For travelers who test positive, CDC recommends the telehealth provider report positive test results to relevant public health authorities in the traveler’s location following local requirements. The telehealth provider should also counsel the traveler on what they and their close contacts should do. This would include not traveling until they complete isolation (if infected) or quarantine (if exposed), in accordance with local requirements.
From the press:
In India a pilot and an aircraft engineer died of COVID on the same day.
Both Taiwan and Singapore are locations where community transmission has been completely eliminated previously, however both of them currently are dealing with clusters of cases which involve airport or airline workers.
CDC Level Changes from 10 May:
Timor-Leste (East Timor): Changing from Level 3 to Level 4 (Avoid all travel)
Nepal: Changing from Level 3 to Level 4
Trinidad and Tobago: Changing from Level 3 to Level 4
Ivory Coast: Changing from Level 4 to Level 3 (Avoid non-essential travel)
Cambodia: Changing from Level 2 to Level 3
Mozambique: Changing from Level 4 to Level 3
United Kingdom: Changing from Level 4 to Level 3
Israel, including the West Bank and Gaza: Changing from Level 3 to Level 2 (Avoid non-essential travel if at high risk severe disease)
French Polynesia (France): Changing from Level 3 to Level 2
Anguilla (U.K.): Changing from Level 1 to Level 2
Hong Kong SAR (China): Changing from Level 2 to Level 1 (Everyday precautions)
Another update soon.
IATA Medical Advisor