Study: New Omicron sub-lineages can dodge immunity

A healthcare worker speaks with a woman queuing for a PCR Covid-19 test at the Lancet laboratory in Johannesburg on Nov 30, 2021. (EMMANUEL CROSET / AFP)

JOHANNESBURG / SANTIAGO / LISBON – Two new sublineages of the Omicron coronavirus variant can dodge antibodies from earlier infection well enough to trigger a new wave, but are far less able to thrive in the blood of people vaccinated against COVID-19, South African scientists have found.

The scientists from multiple institutions were examining Omicron's BA.4 and BA.5 sublineages – which the World Health Organization last month added to its monitoring list. They took blood samples from 39 participants previously infected by Omicron when it first showed up at the end of last year.

South Africa may be entering a fifth COVID wave earlier than expected, officials and scientists said on Friday, blaming a sustained rise in infections that seems to be driven by the BA.4 and BA.5 Omicron sub-variants

Fifteen were vaccinated – eight with Pfizer's shot; seven with J&J's — while the other 24 were not.

"The vaccinated group showed about a 5-fold higher neutralization capacity … and should be better protected," said the study, a pre-print of which was released over the weekend.

ALSO READ: Moderna: Dual booster with Beta more effective vs Omicron

In the unvaccinated samples, there was an almost eightfold decrease in antibody production when exposed to BA.4 and BA.5, compared with the original BA.1 Omicron lineage. Blood from the vaccinated people showed a threefold decrease.

South Africa may be entering a fifth COVID wave earlier than expected, officials and scientists said on Friday, blaming a sustained rise in infections that seems to be driven by the BA.4 and BA.5 Omicron sub-variants.

Only about 30 percent of South Africa's population of 60 million is fully vaccinated.

"Based on neutralization escape, BA.4 and BA.5 have potential to result in a new infection wave," the study said.

Chile

Chile on Saturday reported 2,124 new COVID-19 infections and 18 deaths in one day, bringing the total caseload to 3,558,631 and national death toll to 57,527, its health ministry said.

According to the ministry's daily report, the COVID-19 positivity rate in the last 24 hours was 4.65 percent nationally and 6.72 percent in the Santiago Metropolitan Region.

The ministry also said that there were 9,004 active cases in the South American country and that infections fell by 35 percent in the last two weeks, with 15 of the country's 16 regions showing a decline in cases.  

Portugal

The COVID-19 pandemic maintains "very high transmissibility, with a stable trend," according to a report released on Saturday by the Portuguese Directorate-General for Health (DGS) and the National Institute of Health Doctor Ricardo Jorge (INSA).

The Portuguese health authorities therefore advise the maintenance of "epidemiological surveillance and individual protection measures in the highest risk groups, as well as booster vaccination."

According to the most recent epidemiological bulletin from the DGS, Portugal recorded 57,267 cases of COVID-19 and 119 deaths from the virus in the last week.

The incidence of the disease in the accumulated period of seven days is 556 cases per 100,000 inhabitants, which represents a decrease of 5 percent on average, with the transmissibility index being 1.02.

READ MORE: COVID-19: Portugal removes mask mandates

There were 1,208 people admitted to Portuguese hospitals for COVID-19, practically the same number as the previous week, with 49 being in intensive care units (ICU).

This week, the Portuguese government announced the end of free testing for COVID-19, justifying that actions will be focused on patients with symptoms and on the groups most vulnerable to the disease.