Credit ACIP/CDC
#16,438
Although being fully vaccinated (and boosted) by an mRNA COVID vaccine is believed to provide substantial protection against infection and (more importantly) severe illness from the Omicron (and Delta) variants, how much protection they provide - and for how long - remain largely undetermined.
Of the two variants, Omicron appears to be better able to evade the protection of these vaccines, although we've see significant breakthrough infections with Delta as well.
Laboratory studies have shown a reduced neutralisation capacity of sera from vaccine recipients and convalescent sera against the Omicron VOC compared to other SARS-CoV-2 variants, and a recent Technical Briefing from the UK stated:
The technical briefing also includes early analysis of vaccine effectiveness against the Omicron variant compared to Delta.
It showed that the AstraZeneca and Pfizer-BioNTech vaccines provided much lower levels of protection against symptomatic infection compared to the protection that they provide against Delta. However, the preliminary data showed effectiveness against the new variant appears to increase considerably in the early period after a booster dose, providing around 70% to 75% protection against symptomatic infection.
Today we've a new preprint from Denmark's SSI that examines the relative protection afforded by the Pfizer and Moderna mRNA vaccines against Delta and Omicron, and the apparent `boost' in protection provided by a 3rd (booster) shot of the Pfizer vaccine.
This study also finds a significantly reduced VE against Omicron from the initial 2-dose vaccination series, and a rapid decline over several months.
They report the Pfizer booster restores the VE to roughly 54% (which is lower than the UK estimate), although they don't have enough data to determine how protective it may be against severe illness.
First a link, and the Abstract from the preprint. Followed by a press release from the Statens Serum Institut. I'll have a postscript after the break.
Vaccine effectiveness against SARS-CoV-2 infection with the Omicron or Delta variants following a two-dose or booster BNT162b2 or mRNA-1273 vaccination series: A Danish cohort study
Christian Holm Hansen, Astrid Blicher Schelde, Ida Rask Moustsen-Helms, Hanne-Dorthe Emborg, Tyra Grove Krause, Kaare Moelbak, Palle Valentiner-Branth, The Infectious Disease Preparedness Group at Statens Serum Institut
doi: https://doi.org/10.1101/2021.12.20.21267966
Abstract
In this brief communication we are showing original research results with early estimates from Danish nationwide databases of vaccine effectiveness (VE) against the novel SARS-CoV-2 Omicron variant (B.1.1.529) up to five months after a primary vaccination series with the BNT162b2 or mRNA-1273 -19 vaccines.
Our study provides evidence of protection against infection with the Omicron variant after completion of a primary vaccination series with the BNT162b2 or mRNA-1273 vaccines; in particular, we found a VE against the Omicron variant of 55.2% (95% confidence interval (CI): 23.5 to 73.7%) and 36.7% (95% CI: 69.9 to 76.4%) for the BNT162b2 and mRNA-1273 vaccines, respectively, in the first month after primary vaccination. However, the VE is significantly lower than that against Delta infection and declines rapidly over just a few months.
The VE is re-established upon revaccination with the BNT162b2 vaccine (54.6%, 95% CI: 30.4 to 70.4%).
Study shows the difference between the effect of PfizerBioNTech's and Moderna's vaccines on the delta and omicron variant
A new study shows an estimated protection against infection with the omicron variant of 54.6% among people aged 60 and over who have recently been revaccinated with the vaccine from Pfizer-BioNTech. Against delta, the vaccine effect is measured at 81.2%Last edited December 22, 2021
The protection of the Covid-19 vaccines against the omicron variant decreases over time, but increases again after revaccination.
This is the conclusion of a new study from the Statens Serum Institut (SSI). Here, Acting Head of Department Palle Valentiner-Branth and his colleagues have looked at how well the vaccines from Pfizer-BioNTech and Moderna protect against the omicron variant in relation to the delta variant. The study is based on analyzed data from DKK 3 million. persons.
The study has just been published in a so-called preprint version, which has not yet been peer-reviewed.
Read the preprint version of the study.
Important knowledge
“The Omikron variant is currently spreading rapidly all over the world - also in Denmark. That is why it is important to estimate how much protection the covid-19 vaccines provide against this particular variant, ”says Palle Valentiner-Branth.
The researchers at SSI have investigated how high protection the vaccines provide against SARS-CoV-2 infection with the omicron or delta variant after the primary vaccination course and revaccination, respectively.
The study showed that among those who had recently undergone a primary vaccination course, the estimated protection against infection with the omicron variant was 55.2% (95% confidence interval: 23.5 to 73.7%) for the Pfizer-BioNTech vaccine and 36.7% (69.9 to 76.4% ) for the Modern Vaccine compared to unvaccinated persons. But with rapid declining effect over the course of five months.
In comparison, the estimated protection against infection with the delta variant was higher and better preserved during the same period. It was thus up to 81.2% for the Pfizer-BioNTech vaccine.
Revaccination increases protection
As I said, the researchers also looked at how much protection the vaccines provide when being revaccinated.
Among people aged 60 and over who had recently been revaccinated with the Pfizer-BioNTech vaccine, an estimated protection against infection with the omicron variant was 54.6% (30.4 to 70.4%) compared to people who had undergone a primary vaccination course.
“We see that the protection is lower and falls faster against the omicron than against the delta variant after a primary vaccination course. Revaccination with the vaccine from Pfizer-BioNTech protects against infection with the omicron variant among people aged 60 and over who have recently been revaccinated, ”says Palle Valentiner-Branth.
The studies continue at SSI
It is not yet possible to estimate the protection against covid-19-related hospitalization with the omicron variant. However, this will be monitored on an ongoing basis at SSI.
“We now have a preliminary picture of the extent to which the vaccines from Pfizer-BioNTech and Moderna work against the omicron variant. And we will continue to investigate the vaccine effectiveness against this variant. Including how long the protection is ", concludes Palle Valentiner-Branth.
While disappointing, these results are not unexpected. We've seen plenty of evidence over the past few weeks that Omicron - with more than 30 mutations in its spike gene - evades prior immunity better than Delta.
While a recent booster shot only appears to provide a 55% VE against infection, that is still worth having (roughly what the flu shot provides each year), and it is expected to be more protective against serious illness and death.
This study also focused on those over the age of 60, and so the VE is likely higher in younger people. On the other hand, we don't know how long this `boost' lasts.
The upshot is that even those who are fully vaccinated (included the boosted) are at least partially susceptible to Omicron infection, and that should exacerbate size of the wave of COVID coming our way.
Not ideal, obviously. But better to have 50% protection than none at all. And that level of protection can be increased by wearing a face mask in public, avoiding crowds, and good hand hygiene. And its also worth reminding my readers that Now, More Than Ever Before, Get A `Flu Buddy'.Hopefully, most will experience less severe illness due to the vaccine, but not everyone will come away unscathed.
