Omicron is displacing delta science

Omicron infection also produced immunity against Delta. This means someone who has been infected with delta is largely immune to subsequent delta infection. Therefore delta will soon have no one to infect, therefore will go away.

Omicron infection enhances neutralizing immunity against the Delta variantOmicron infection enhances neutralizing immunity against the Delta variant

Africa Health Research Institute, Durban, South Africa

School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal

Omicron has been shown to be highly transmissible

Omicron has extensive evasion of neutralizing antibody immunity,

elicited by vaccination and previous SARS-CoV-2 infection.

Omicron infections are rapidly expanding worldwide often in the face of high levels of Delta infections.

Question

Do omicron antibodies neutralise delta virus variant?

Does neutralizing immunity elicited by Omicron also enhances neutralizing immunity against the Delta variant?

Method

Isolated the omicron and delta virus

Tested these against the plasma of 15 confirmed omicron cases

Used a live virus neutralization assay

(Vero E6 cells were propagated in complete growth medium)

Calculated the focus reduction neutralization test (FRNT50)

Volunteers

Previously vaccinated

Unvaccinated individuals who were infected with SARS-CoV-2 in the Omicron infection wave

Recruited soon after symptom onset

We then measured their ability to neutralize both Omicron and Delta virus at enrolment,

versus a median of 14 days after enrolment.

Neutralization of Omicron increased 14-fold over this time,

showing a developing antibody response to omicron

Also

Enhancement of Delta virus neutralization, increased 4.4-fold.

Therefore

The increase in Delta variant neutralization in individuals infected with Omicron may result in decreased ability of Delta to re-infect

Also

Emerging data indicating that Omicron is less pathogenic than Delta

Therefore

Cross immunity from omicron to delta may have positive implications in terms of decreasing the Covid-burden of severe disease.

More science

The ability of one variant to elicit immunity which can cross-neutralize another variant varies by variant

Immunity elicited by Delta infection

Does not cross-neutralize Beta virus

Immunity elicited by Beta infection

Does not cross-neutralize Delta well

Participants in this study

Many probably previously infected

More than half were vaccinated

Therefore activation of antibody immunity from previous infection and/or vaccination is possible

Implications

These results are consistent with Omicron displacing the Delta variant

As cross immunity makes re-infection with Delta less likely

(But previous delta exposure will not protect from symptomatic omicron infection)

If indeed Omicron is less pathogenic than Delta

The incidence of Covid-19 severe disease would be reduced

Infection may shift to become less disruptive to individuals and society