Could face masks be a painless "inoculation"?
The difficult reality of developing a vaccine for Covid is becoming more evident as trials by Oxford-AstraZeneca and Johnson and Johnson have been halted. Even though there are tens of other trials in play, achieving a persuasive and safe outcome, let alone establishing manufacture and distribution, must still be many months away.
Noting of course that this is not medical advice it interests us that the evidence is mounting that masks may be performing an equivalent function to a vaccine.
This theory is based on the concept that masks while limiting exposure to the virus but may still let a small amount get through to the wearer. That small dose, or inoculum, is enough to stimulate the body's response to make anti bodies and prevent the virus from overwhelming the body with the result that your symptoms are less severe or are not evident at all ie asymptomatic.
Our April blog touched on this concept, brought to light by Rishi Desai, MD MPH, Chief Medical Officer at Osmosis and former Outbreak Investigator at the USA Centre for Disease Control.
More recently we've heard it from the Spotify Podcast: Emergency Docs which comes from California and is coincidentally hosted by one of our ArmaSkin Ambassadors. In Episode 20 they say that when wearing a mask the wearer "may still be exposed to Covid but it may be small enough for the body to fight off the infection without ever causing symptoms...." They do however stress that "The safest bet is still avoidance."
Separately, contained in a youtube video by Dr Chris Martenson, was a series of specific examples compiled by Monica Gandhi MD, MPH, who is Professor of Medicine and Associate Division Chief of the Division of HIV, Infectious Diseases, at at UCSF San Francisco General Hospital.
Here are a few of the highlights:
* The idea of the dose level impacting how sick the recipient gets has been well known in animal studies for many years. ie the more virus an animal is exposed to the sicker it becomes.
*From closed settings, such as cruise ships, For example, one of the earliest estimates of the rate of asymptomatic infection due to SARS-CoV-2 was in the 20% range from a report of a COVID-19 outbreak on the Diamond Princess cruise ship. In a more recent report from a different cruise ship outbreak where all passengers were issued surgical masks and all staff provided N95 masks after the initial case of COVID-19 on the ship was detected. In this closed setting with masking, where 128 of 217 passengers and staff eventually tested positive for SARS-CoV-2 ,the majority of infected patients on the ship (81%) remained asymptomatic, compared with 18% in the cruise ship outbreak without masking.
*A report from a pediatric hemodialysis unit in Indiana, where all patients and staff were masked, demonstrated that staff rapidly developed antibodies to SARS-CoV-2 after exposure to a single symptomatic patient with COVID-19. In the setting of masking, however, none of the new infections was symptomatic.
*in a recent outbreak in a seafood processing plant in Oregon where all workers were issued masks each day at work, the rate of asymptomatic infection among the 124 infected was 95%. An outbreak in a Tyson chicken plant in Arkansas with masking also showed a 95% asymptomatic rate of infection.
If you'd like to delve further into Monica Gandhi's paper here's a link.
So, even in Australia where the number of active cases is currently being kept quite low, it would seem wise practice to maintain mask wearing well into the future.
If mask wearing is providing greater numbers of asymptomatic cases then the disease will be passed through the population and many sufferers will not think they need testing.
This suggests a complementary testing strategy to monitor how significantly the disease is permeating the population asymptomatically while maintaining comprehensive contact tracing.
Quite a challenge indeed! But common sense will be to mask up especially for those close quarters, end of year get togethers involving older family members.