#15,977
In an unusually robust late Saturday data dump, the UK's PHE has released multiple documents on the B.1.617.2 variant, including a revised Risk Assessment and an initial estimate of vaccine effectiveness against it, along with their 12th Technical Briefing on COVID-19.
All of this comes on the heels of the remarkable and rapid expansion of the B.1.617.2 variant across much of the UK (see Friday's report UK COVID Variant Update: B.1.617.2 Continues to Rise - New VUI (VUI-21MAY-01) Added) over the past few weeks, exhibiting a growth rate many times higher than the B.1.1.7 (aka `UK') variant.
We'll start with the good news, a press release from the PHE which indicates that while (2 doses) of the current vaccines don't protect against the B.1.617.2 variant quite as well as against earlier variants, they still offer a high degree of protection.
Vaccines highly effective against B.1.617.2 variant after 2 doses
New study by PHE shows for the first time that 2 doses of the COVID-19 vaccines are highly effective against the B.1.617.2 variant first identified in India.
From:Public Health England Published 22 May 2021
Vaccine effectiveness against symptomatic disease from the B.1.617.2 variant is similar after 2 doses compared to the B.1.1.7 (Kent) variant dominant in the UK, and we expect to see even higher levels of effectiveness against hospitalisation and death.
The study found that, for the period from 5 April to 16 May:
- the Pfizer-BioNTech vaccine was 88% effective against symptomatic disease from the B.1.617.2 variant 2 weeks after the second dose, compared to 93% effectiveness against the B.1.1.7 variant
- 2 doses of the AstraZeneca vaccine were 60% effective against symptomatic disease from the B.1.617.2 variant compared to 66% effectiveness against the B.1.1.7 variant
- both vaccines were 33% effective against symptomatic disease from B.1.617.2, 3 weeks after the first dose compared to around 50% effectiveness against the B.1.1.7 variant
The analysis included data for all age groups from 5 April to cover the period since the B.1.617.2 variant emerged. It included 1,054 people confirmed as having the B.1.617.2 variant through genomic sequencing, including participants of several ethnicities. Data published on Thursday 20 May for vaccine effectiveness covered the period since December for those aged over 65.The difference in effectiveness between the vaccines after 2 doses may be explained by the fact that rollout of second doses of AstraZeneca was later than for the Pfizer-BioNTech vaccine, and other data on antibody profiles show it takes longer to reach maximum effectiveness with the AstraZeneca vaccine.As with other variants, even higher levels of effectiveness are expected against hospitalisation and death. There are currently insufficient cases and follow-up periods to estimate vaccine effectiveness against severe outcomes from the B.1.617.2 variant. PHE will continue to evaluate this over the coming weeks.
Moving on to the revised risk assessment, I've reformatted the text for readability below. You'll notice that the confidence level on current vaccine effectiveness ranges from LOW to MODERATE, confidence in Immunity after natural infection is LOW, and there is not enough data to speak to Infection Severity (compared to B.1.1.7).
Transmissibility between humans Confidence: HIGHTransmissibility appears greater than wild type (first wave) SARS-CoV-2There is an increased growth rate compared to B.1.1.7 in the current context. Secondary attack rates, including household secondary attack rates, are higher for B.1.617.2, but these are not yet corrected for vaccination status. There is early in vitro evidence suggestive of altered growth characteristics in biological model systems. The observed epidemiological growth rate and replacement of B.1.1.7 are unlikely to be due entirely to immune escape, given the improved understanding of antigenic change; it is likely that B.1.617.2 is more transmissible than B.1.1.7. The magnitude of the change in transmissibility remains uncertain.
Infection severity Confidence : N/AInsufficient informationMost cases are recent and there has been insufficient follow up time to allow an assessment of severity. Early warning signals are being monitored with no evidence of increases in hospitalisation in national data
Immunity after natural infection Confidence LOWExperimental evidence of functional evasion of natural immunityPseudovirus and live virus neutralisation using convalescent sera from first wave and B.1.1.7 infections shows a modest reduction in neutralisation which may still be clinically relevant in individuals with low titres. There are small numbers of reinfections detected through national surveillance which would be expected with a prevalent variant. These are being further investigated. There is no signal of an increase in reinfections in individuals in a national healthcare worker cohort study (95% vaccinated); monitoring continues.
Vaccines Confidence : MODERATE after dose 1 LOW after dose 2Evidence of reduced vaccine effectivenessNational vaccine effectiveness monitoring shows a reduction in vaccine effectiveness against symptomatic infection after 1 dose of vaccine for B.1.617.2 compared to B.1.1.7 (moderate confidence).Current data suggest this is an absolute reduction of approximately 20% after 1 dose. Vaccine effectiveness is higher and similar between variants after 2 doses with a possible small reduction for B.1.617.2 (low confidence). Although this is observational data subject to some biases, it holds true across several analytic approaches, is consistent with observed outbreaks, and is supported by pseudovirus and live virus neutralisation data. There are no data on whether prevention of transmission is affected.There are insufficient data on vaccine effectiveness against severe disease. Based on neutralisation data, vaccines are expected to remain effective against severe disease. Monitoring continues
Overall assessment
B.1.617.2 has continued to replace B.1.1.7 but an increase in overall incidence has occurred in only a small number of areas. The observed high growth rate is most likely to be due to a combination of context and transmissibility. There may be a contribution from some degree of immune escape particularly relating to individuals who have had a single vaccine dose. The priority investigations are household secondary attack rate corrected for vaccination, characterisation of the generation time, viral load and period of infectivity, severity analyses, and continued reinfection and vaccine effectiveness monitoring.
This is obviously a mixed bag, since they peg B.1.617.2 to be more transmissible than the (already highly transmissible) B.1.1.7 variant. The jury is still out on increased severity.
Vaccine effectiveness against symptomatic infection appears pretty impressive with the Pfizer mRNA vaccine (> 80%), but only 60% with the AZ vaccine. Confidence in these vaccine numbers is less than robust, however, and these numbers could change.
The $64 question is what all of this means to the pandemic's impact in the UK, and eventually, around the world. For countries or regions with high vaccination rates, B.1.617.2 may be less of a problem, but where vaccination rates are low, it has the potential to replicate what we've been seeing in India for the past month.
The elephant in the room, of course, is that new variants continue to emerge - and while conventional wisdom has long held that mutations are more likely to weaken or attenuate pandemic viruses over time - the B.1.1.7, B.1.617.2, and P.1 variants have done the opposite.
Even if B.1.617.2 ends up being the last `improved' COVID variant, the world has more than enough on its plate to deal with, and so any reports of the pandemic's imminent demise are probably premature.
