BA.5 causes more severe disease

UK infections continue upwards

Reinfections now common

Generally, infections tend to milder the second or third time round

Danny Altmann, professor of immunology, Imperial College London

Omicron is poorly immunogenic, which means that catching it offers little extra protection against catching it again

Prof Tim Spector

There are definitely a lot of people who got Covid at the start of the year who are getting it again,

including some with BA.4/5 who had BA.1/2 just four months ago

rare to be reinfected with within three months

BA.2.12.1, BA.4 and BA.5 escape antibodies elicited by Omicron infection

New sub-variants notably evade the neutralising antibodies elicited by SARS-CoV-2 infection and vaccination

Vaccine boosters based on the BA.1 virus

(e.g. those developed by Pfizer/BioNTech and Moderna)

may not achieve broad-spectrum protection against new Omicron variants

Dr. Onyema Ogbuagu, Yale School of Medicine, Connecticut

My personal bias is that while there may be some advantage to having an Omicron-specific vaccine,

I think it will be of marginal benefit over staying current with the existing vaccines and boosters

Despite immune evasion, the expectation can be that vaccines will still protect against serious disease

What we’ve learned clinically is that it’s most important to stay up-to-date with vaccines

to maintain high levels of COVID-19 antibodies circulating in the blood

Kei Sato, University of Tokyo

New sub-variants may have evolved to refavour infection of lung cells

Risk is potentially greater than that of original BA.2

Dr Stephen Griffin, University of Leeds

It looks as though these things are switching back to the more dangerous form of infection, so going lower down in the lung

Neutralization Escape by SARS-CoV-2 Omicron Subvariants BA.2.12.1, BA.4, and BA.5

Subvariants BA.1 and BA.2, substantial escape from neutralizing antibodies

Subvariants BA.4 and BA.5 have identical sequences of spike protein

Comparison of neutralizing antibody titer WA1/2020 isolate with BA.1, BA.2, BA.2.12.1, and BA.4 or BA.5

Isolate USA-WA1/2020 from an oropharyngeal swab,

returned from China,

who and developed clinical disease,

January 2020 in Washington, USA

In 27 participants, all vaccinated and boosted with Pfizer,

And 27 participants who had been infected with the BA.1 or BA.2 median 29 days earlier (range, 2 to 113 days)

In the vaccine cohort

Participants were excluded,

if they had a history of SARS-CoV-2 infection,

or a positive result on nucleocapsid serologic analysis,

or if they had received another covid vaccine,

or an immunosuppressive medication

Six months after the initial two BNT162b2 immunizations

Neutralizing antibody titer against WA1/2020 = 124

Neutralizing antibody titer against omicron subvarients = 20

Two weeks after administration of the booster dose

Neutralizing antibody titer against WA1/2020 = 5,783

Neutralizing antibody titer against BA.1 = 900

BA.2 = 892

BA.2.12.1 = 410

BA.4 or BA.5 = 275 (21 times lower than 5,783)

What about natural immunity

Among the participants who had been infected with BA.1 or BA.2,

26 had been vaccinated

Median neutralizing antibody titer

WA1/2020 isolate = 11,050

BA.1 = 1,740

BA.2 = 1,910

BA.2.12.1 = 1,150

BA.4 or BA.5 = 590 (18.7 times less than 11,050)

These data show that the BA.2.12.1, BA.4, and BA.5 subvariants substantially escape neutralizing antibodies induced by both vaccination and infection.

SARS-CoV-2 omicron variant has continued to evolve with increasing neutralization escape.

These findings provide immunologic context for the current surges caused by the BA.2.12.1, BA.4, and BA.5 subvariants,

in populations with high frequencies of vaccination and BA.1 or BA.2 infection.


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