Rapid nose swab tests may not detect Omicron quickly enough

A man swabs his nose at a COVID-19 testing on the Martin Luther King Jr. medical campus, Jan 3, 2022, in Los Angeles. (MARCIO JOSE SANCHEZ / AP)

BRASILIA / NEW YORK / OTTAWA / MEXICO CITY / CAIRO / PARIS / MADRID / BERLIN / LONDON / VIENNA – Swabbing the nose with a rapid antigen test will not reliably detect the Omicron variant in the first few days of an infection, so manufacturers should seek US approval to allow users to safely collect samples from the throat as well, according to an infectious diseases expert.

Swabbing the nose with a rapid antigen test will not reliably detect the Omicron variant in the first few days of an infection, according to an infectious diseases expert

The US Food and Drug Administration has expressed concerns over the safety of self throat swabbing.

People can already transmit Omicron to others when it has infected their throat and saliva but before the virus reaches their nose, so swabbing the nostrils too early in the course of infection will not pick it up, Dr Michael Mina, formerly of the Harvard T.H. Chan School of Public Health and now chief science officer at eMed, said during a news conference on Thursday.

A study released on Wednesday on medRxiv ahead of peer review looked at 29 Omicron-infected workers in high-risk professions who had PCR and antigen tests done simultaneously on multiple days. The PCR tests of saliva detected the virus on average three days before the rapid nose-swab samples became positive.

"When people test negative by rapid antigen, they can still have very infectious viral loads and transmit to other people," said study leader Blythe Adamson of New York-based risk reduction company Infectious Economics LLC.

A positive antigen test is very reliable, Mina noted.


Austrian Chancellor Karl Nehammer tested positive for COVID-19 on Friday, the Federal Chancellery said, adding that he was infected by a member of his security team.

Nehammer shows no symptoms and carries out his official duties from home via video and telephone meetings. He will not attend in-person meetings in the next few days, the Chancellery said, adding that Nehammer has received three COVID-19 vaccine doses.

Meanwhile, the chancellor's wife and children tested negative on Friday.


Brazil has had 63,292 new cases of the coronavirus reported in the past 24 hours, and 181 deaths from COVID-19, the health ministry said on Friday.

That is the highest number of daily infections since July last year. Health experts say the Omicron variant is spreading in the South American country.

Brazil has now registered 22,450,222 cases since the pandemic began, while the official death toll has risen to 619,822. Brazil's COVID-19 death toll trails only the United States and Russia, according to Reuters calculations.


Canadian Health Minister Jean-Yves Duclos on Friday warned some of the country's 10 provinces that they needed to do more to fight the Omicron coronavirus variant and prevent healthcare systems from being swamped.

New daily cases of COVID-19 soared by 65 percent in the last week across Canada, and hospitals say it is becoming increasingly hard to maintain staffing levels

New daily cases of COVID-19 soared by 65 percent in the last week across Canada, and hospitals say it is becoming increasingly hard to maintain staffing levels.

Duclos said provinces should pay attention to Ontario and Quebec, which together account for around 61 percent of Canada's population of 38.4 million. Both have reimposed severe restrictions on businesses and gatherings.

"Those two provinces are going through a very difficult time. That, however, is a signal to other provinces … that they may be just a week, perhaps two weeks behind," he said.

This was important because the federal government did not have sufficient resources to give the provinces all the help they wanted, he told a briefing.

Chief medical officer Theresa Tam said that while the risk of hospitalization was lower for Omicron compared to the Delta variant, "the sudden acceleration of Omicron and enormous volume of cases is driving severe illness trends".

Tam and Duclos reiterated that Canadians should get inoculated against COVID-19. Official data show that as of Dec 18, 87.3 percent of Canadians aged 12 and older had received two shots while the figure for children aged 5 to 12 was just 1.3 percent.

Members of the public queue outside a pharmacy to receive COVID-19 antigen tests in Paris on Jan 6, 2022.


France on Friday registered 328,214 new coronavirus cases in the last 24 hours, around 70,000 more than on the previous day but still slightly below the historic record of 332,252 new cases reached on Wednesday, official data showed.


German Chancellor Olaf Scholz and regional leaders tightened the rules for restaurant and bar visits but shortened COVID-19 quarantine periods on Friday in response to the Omicron variant.

Scholz added that all 16 state leaders supported the implementation of a general vaccination mandate and that the Bundestag lower house of parliament would discuss drafts of it soon.

Under new measures decided on Friday, people in Germany who have received a booster shot will not have to isolate after being in contact with someone who was infected with the coronavirus.

They also are exempt from stricter rules on dining requiring a negative test result in addition to proof of vaccination or recovery to enter a restaurant or bar, as part of an effort to encourage more people to get a booster shot.

Omicron now accounts for 44 percent of coronavirus infections in Germany, the Robert Koch Institute (RKI) for infectious disease said in its weekly report. It said 41.6 percent of people had received a booster shot.

Germany also shortened quarantine for infected people and their contacts to 10 days from 14, though they can end the quarantine period after seven days with a negative test.

Children will be able to return to school with a negative PCR or antigen test after five days.


Mexico's health regulator has granted authorization for emergency use of drugmaker Merck's COVID-19 pill Molnupiravir, President Andres Manuel Lopez Obrador said on Friday.

The health regulator, COFEPRIS, confirmed the approval in a statement later in the day.

COFEPRIS was expected to soon also approve Pfizer's Paxlovid pill to treat COVID-19, Lopez Obrador added at a regular news conference. Both medications were approved last month in the United States.

Molnupiravir was developed with Ridgeback Biotherapeutics and shown to reduce hospitalizations and deaths by around 30 percent in a clinical trial of high-risk individuals early in the course of the illness.

Lopez Obrador said he planned to make both medications available in public hospitals.


Morocco has authorized the emergency use of Merck &Co's molnupiravir medication for COVID-19 patients, Moroccan state news agency reported on Friday, quoting Bushra Maddah, the drugs chief at the country's health ministry.

The North African country reported 6,428 cases, and 13 deaths of the coronavirus on Friday, bringing the overall numbers to 990,057 and 14,896, respectively.


Two doses of the Pfizer and BioNTech COVID-19 vaccine are highly protective against a rare but often serious condition in children that causes organ inflammation weeks after COVID-19 infections, a US Centers for Disease Control and Prevention report said on Friday.

Two doses of the Pfizer and BioNTech COVID-19 vaccine are highly protective against a rare but often serious condition in children that causes organ inflammation weeks after COVID-19 infections, a US Centers for Disease Control and Prevention report said

The vaccine was estimated to be 91 percent effective in preventing Multisystem Inflammatory Syndrome in Children (MIS-C) in 12- to 18-year-olds, the study said. MIS-C causes inflammation in children organs including the heart, lungs, kidneys and brain two to six weeks after a mild or asymptomatic infection.

The estimate is based on the assessment of 283 hospitalized patients aged 12-18 years at 24 children's hospitals in 20 states between July and early December, when the prevalence of the Delta coronavirus variant was high.

All 38 MIS-C patients requiring life support were unvaccinated, the study said.

The results add to a growing body of evidence that vaccination against COVID-19 is likely to prevent disease-related complications in children, including MIS-C, the report said. It was not previously known whether the Pfizer/BioNTech vaccine prevented the condition.

South Africa

Doctors in one of the cities where Omicron was first identified say the surge driven by the new variant has been marked by less serious disease than earlier waves of the pandemic and there are clear signs that case and hospital admission rates may decline over the next few weeks.

At the Steve Biko Academic Hospital in the City of Tshwane, doctors compared 466 infected patients admitted since mid-November 2021 to 3,976 patients admitted before then. The mortality rate during the Omicron surge was 4.5 percent, compared to 21.3 percent in the earlier period, they reported in the International Journal of Infectious Diseases. Omicron patients were discharged after an average of 4 days, compared to 8.8 days for patients with earlier variants. At the peak of the Omicron surge, the number of beds filled with infected patients was half of that in the earlier period, and 63 percent of Omicron patients were hospitalized for other reasons, with the virus only detected by mandatory tests.

"The Omicron outbreak has spread and declined… with unprecedented speed, peaking within four weeks," the researchers said. 

They noted that outcomes may vary in countries with different population characteristics and levels of immunity from infection and vaccination. But if the pattern seen in South Africa "continues and is repeated globally … Omicron may be a harbinger of the end of the epidemic phase" of the health crisis.


Spain's 14-day COVID-19 infection rate rose by 148 points to 2,722.72 cases per 100,000 people, the health ministry said on Friday, compared to 2,574.46 on Wednesday when the last figures were released before a public holiday on Thursday.

The number of cases of coronavirus rose by 242,440 on Friday compared with Wednesday.

The percentage of hospital beds occupied by patients with coronavirus was 11.79 percent on Friday, compared to an earlier wave of the pandemic last year when 24 percent of hospital beds were occupied by people with COVID-19 on Jan 28.

The number of patients with COVID-19 in intensive care units rose to 22.06 percent but this was well below the figure of almost a year ago when 42.84 percent of intensive beds were occupied by patients with the virus on Jan 28 last year.


Booster jabs are still providing high levels of protection for older people against severe disease from the Omicron coronavirus variant and there is no need for now for people to have a fourth shot, British health officials said on Friday.

Around three months after receiving a third jab, protection against hospitalization among those aged 65 and over remained at about 90 percent, the UK Health Security Agency said.

"The data is highly encouraging and emphasizes the value of a booster jab," Wei Shen Lim, chair for COVID-19 immunization on the government's Joint Committee on Vaccination and Immunization, said in a statement.

By comparison, with only two vaccine doses, protection against severe disease for the over-65s dropped to around 70 percent after three months and to 50 percent after six months, the UKHSA said.


COVID-19 hospitalizations in the United States are poised to hit a new high as early as Friday, according to a Reuters tally, surpassing the record set in January of last year as the highly contagious Omicron variant fuels a surge in infections.

Hospitalizations have increased steadily since late December as Omicron quickly overtook Delta as the dominant coronavirus variant in the United States, although experts say Omicron will likely prove less deadly than prior iterations.

Health officials have nevertheless warned that the sheer number of infections caused by Omicron was placing a strain on hospitals, some of which are struggling to keep up with the influx of patients because their own workers are out sick.

The United States reported 662,000 new COVID-19 cases on Thursday, the fourth highest daily US total, just three days after a record of nearly 1 million cases was hit, according to the Reuters tally.

US COVID hospitalizations approached 123,000, appearing poised to top the record above 132,000, according to the tally. Deaths, a lagging indicator, remain fairly steady at about 1,400 a day, well below last year's peak.