Pfizer CEO Bourla: Omicron-specific Covid vaccine will be ready by March 11,699 views • Jan 10, 2022 • Pfizer CEO Albert Bourla sits down with CNBC's Meg Tirrell and the 'Squawk Box' team to discuss the company's Covid-19 vaccine booster strategy, including a potential shot targeting the omicron variant.
Coronavirus loses 90% of its ability to infect us within 20 minutes of becoming airborne – with most of the loss occurring within the first five minutes, the world’s first simulations of how the virus survives in exhaled air suggest.
The findings re-emphasise the importance of short-range Covid transmission, with physical distancing and mask-wearing likely to be the most effective means of preventing infection. Ventilation, though still worthwhile, is likely to have a lesser impact.
“People have been focused on poorly ventilated spaces and thinking about airborne transmission over metres or across a room. I’m not saying that doesn’t happen, but I think still the greatest risk of exposure is when you’re close to someone,” said Prof Jonathan Reid, director of the University of Bristol’s Aerosol Research Centre and the study’s lead author.
“When you move further away, not only is the aerosol diluted down, there’s also less infectious virus because the virus has lost infectivity [as a result of time].”
Until now, our assumptions about how long the virus survives in tiny airborne droplets have been based on studies that involved spraying virus into sealed vessels called Goldberg drums, which rotate to keep the droplets airborne. Using this method, US researchers found that infectious virus could still be detected after three hours. Yet such experiments do not accurately replicate what happens when we cough or breathe.
Instead, researchers from the University of Bristol developed apparatus that allowed them to generate any number of tiny, virus-containing particles and gently levitate them between two electric rings for anywhere between five seconds to 20 minutes, while tightly controlling the temperature, humidity and UV light intensity of their surroundings. “This is the first time anyone has been able to actually simulate what happens to the aerosol during the exhalation process,” Reid said.
The study, which has not yet been peer-reviewed, suggested that as the viral particles leave the relatively moist and carbon dioxide-rich conditions of the lungs, they rapidly lose water and dry out, while the transition to lower levels of carbon dioxide is associated with a rapid increase in pH. Both of these factors disrupt the virus’s ability to infect human cells, but the speed at which the particles dry out varies according to the relative humidity of the surrounding air.
When this was lower than 50% – similar to the relatively dry air found in many offices – the virus had lost around half of its infectivity within five seconds, after which the decline was slower and more steady, with a further 19% loss over the next five minutes. At 90% humidity – roughly equivalent to a steam or shower room – the decline in infectivity was more gradual, with 52% of particles remaining infectious after five minutes, dropping to about 10% after 20 minutes, after which these was no difference between the two conditions.
The Dynamics of SARS-CoV-2 Infectivity with Changes in Aerosol Microenvironment
Abstract Understanding the factors that influence the airborne survival of viruses such as SARS-CoV-2 in aerosols is important for identifying routes of transmission and the value of various mitigation strategies for preventing transmission. We present measurements of the stability of SARS-CoV-2 in aerosol droplets (~5-10µm equilibrated radius) over timescales spanning from 5 seconds to 20 minutes using a novel instrument to probe survival in a small population of droplets (typically 5-10) containing ~1 virus/droplet. Measurements of airborne infectivity change are coupled with a detailed physicochemical analysis of the airborne droplets containing the virus. A decrease in infectivity to ~10 % of the starting value was observable for SARS-CoV-2 over 20 minutes, with a large proportion of the loss occurring within the first 5 minutes after aerosolisation. The initial rate of infectivity loss was found to correlate with physical transformation of the equilibrating droplet; salts within the droplets crystallise at RHs below 50% leading to a near instant loss of infectivity in 50–60% of the virus. However, at 90% RH the droplet remains homogenous and aqueous, and the viral stability is sustained for the first 2 minutes, beyond which it decays to only 10% remaining infectious after 10 minutes. The loss of infectivity at high RH is consistent with an elevation in the pH of the droplets, caused by volatilisation of CO2 from bicarbonate buffer within the droplet. Three different variants of SARS-CoV-2 were compared and found to have a similar degree of airborne stability at both high and low RH.
Covid-19 hospitalization rates among children are soaring in the United States, with an average of 4.3 children under 5 per 100,000 hospitalized with an infection as of the week ending January 1, up from 2.6 children the previous week, according to data from the US Centers for Disease Control and Prevention.
This represents a 48% increase from the week ending December 4, and the largest increase in hospitalization rate this age group has seen over the course of the pandemic.
"For our youngest children, those who are not yet eligible for vaccination, it's critically important that we surround them with people who are vaccinated to provide them protection," CDC director Dr. Rochelle Walensky said Friday.
New hospital admissions for children under 18 with confirmed Covid-19 are already at a record level, at an average of 797 each day, according to data from the CDC and the US Department of Health and Human Services. This is the highest it has ever been, and it's an 80% increase over the previous week.
"I would say the best way to keep those children protected is to vaccinate them as they're eligible and surround them by siblings and parents who are vaccinated themselves," Walensky said.
Over the course of the Covid-19 pandemic, close to 82,000 children have been hospitalized with Covid-19, according to most recent data from the CDC.
CDC updates prevention guidance in schools Aligning with its latest quarantine and isolation recommendations, the CDC on Thursday updated guidance for Covid-19 prevention in K-12 schools.
Students, teachers and staff with Covid-19 should stay home and isolate away from others for at least five days, the guidance said. Day 0 is considered the first day of symptoms or the day of a positive viral test for people who do not have symptoms.
People whose symptoms are improving can leave isolation after five full days if they are fever-free for 24 hours, the CDC said. They should wear a mask around others for an additional five days.
Children who have been exposed to the coronavirus and have not been fully vaccinated should quarantine for at least five days after their last close contact with a person who has Covid-19, the guidance said. Adults who are not vaccinated against Covid-19 or who have not received a booster shot are also advised to follow this recommendation.
For the first time since July, the CDC will hold an independent telebriefing on the pandemic on Friday. The CDC usually participates in joint briefings with officials from the White House or the National Institutes of Health.
Australia reported a record high of COVID-19 deaths Tuesday, and its second-largest state declared an emergency in hospitals to cope with surging patient admissions and a staffing shortage due to the coronavirus.
The 74 deaths occurred in its three most populous states. New South Wales reported 36, Victoria reported 22 and Queensland 16. The previous daily record was 59 coronavirus-related deaths on Sept. 4, 2020.
Federal Health Minister Greg Hunt said there were signs that New South Wales’ infection rate was peaking and Victoria was near a plateau.
The New South Wales government has ruled out a return to lockdown to counter the highly contagious omicron variant. In October, Sydney ended a 108-day lockdown because the population of Australia’s most populous city was largely vaccinated.
Another lockdown would have “substantial consequences for men and women right across the state in terms of being able to provide food on the table for their family,” state Premier Domonic Perrottet told Australian Broadcasting Corp.
Victoria declared an emergency for hospitals in its state capital, Melbourne, and several regional hospitals from midday Wednesday because of staff shortages and a surge in patient admissions. About 5,000 staff are absent because they are either infected or close contacts.
“We’ve reached a point in our healthcare system where it’s juggling extreme workforce shortages … alongside a vast number of patients with COVID-19 who require hospitalization, alongside that an extraordinary workforce that are absolutely exhausted,” Acting Health Minister James Merlino said.
A emergency declaration means additional capability and capacity need to be mobilized to receive an influx of patients. Some hospital staff may be recalled from leave and more services will be deferred. Physiotherapists and medical students will be asked to take on nursing duties.
It is the first time the emergency has been activated in multiple hospitals across the state.
More than 2,700 people have died with COVID-19 in Australia, which has a population of 26 million.