This Indian-Origin Harvard Student Has Found A Safe Way To Decontaminate N95 Masks In Microwave

With PPEs in short supply, researchers and scientist across the world have looked into the viability of reusing masks and the decontamination process for the same.

An Indian PhD student from Harvard University in the U.S., has found an innovative way to decontaminate N95 masks.

Twitter/@TanushJagdish

The frontline fighters against the virus, be it the law enforcement authorities or our doctors and nurses, have on multiple occasions faced a shortage of PPE kits. For those at the forefront of the pandemic, the decontamination technique can be a life-saver.

Jagdish, who is currently studying ¡®Program for Systems, Synthetic and Quantitative Biology¡¯ at Harvard University, explained the decontamination method on Twitter.

Twitter/@TanushJagdish

"MS2 is a virus which infects the bacterium E. coli, not humans. We can make billions of new MS2 everyday by infecting E. coli with old MS2 and harvesting new MS2 once the E. coli are infected. We can also use a method called 'plaque assays' to measure how many viruses remain on masks. For this, we take all the viruses on a mask and add them on to E. coli growing on a petri dish," News18 quoted Jagdish as saying.

"The viruses will make little holes or 'plaques' in the E. coli. By counting the number of plaques on the petri dish, we can extrapolate and back-calculate how many viruses were on the mask in the first place," Jagdish adds.

Heat is generally one of the easiest methods used in decontamination across all major laboratories and hospitals. "Steam is incorporated within these methods because it can permeate through layers and increase the overall surface area and volume of decontamination. Moist heat is known to be much better at killing microbes because it denatures the overall structures of important enzymes, which end up coagulating and crashing out of solution," News 18 quoted him as saying.

In a Twitter thread Tanush Jagdish explained: "N95 respirator supply is scarce. We have tested multiple methods for N95 decontamination over the past month, including industrial scale VHP treatment for hospitals (now FDA approved). Here we share new work on easily accessible microwave-steam decontamination."

Take a look at the thread below:

#1

N95 respirator supply is scarce. We have tested multiple methods for N95 decontamination over the past month, including industrial scale VHP treatment for hospitals (now FDA approved).

Here we share new work on easily accessible microwave-steam decontamination. Please RT! (1/8) pic.twitter.com/wpQnaMBJVF

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#2

We applied about 10 million live MS2 viruses on different regions of N95 masks. Microwaving this mask on a wide glass container (17 by 17 cm) containing 60 mL water for 3 minutes eliminated close to all viruses. An average of 99.9999% or 6log reduction. (2/8) pic.twitter.com/WCPAaDVPcl

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#3

We measured filtration efficiency of masks after microwave treatment keeping with OSHA guidelines. N95 fit and function was intact even after 20 sequential microwave-steam decontamination treatments.

NOTE: Metal strap on the mask did NOT cause any issue. (3/8)

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#4

The idea is that steam generated from container is sufficient to permeate mask membranes and kill close to all 10 million viruses. Using any microwave-safe mesh should work. We used easily available plastic meshes that come with clementines and oranges. (4/8) pic.twitter.com/iVI9Mc43wj

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#5

Given its protein capsid, the positive strand RNA virus MS2 is harder to disinfect than SARS-Cov-2 (which has a lipid membrane). For instance, we found dry heat even up to 100 ¡ãC to be completely ineffective against MS2 on masks, while SARS-CoV-2 is killed at 70-80 ¡ãC. (5/8) pic.twitter.com/QgDe9HyMPY

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#6

Of all methods currently available, vaporized hydrogen peroxide (VHP) is likely most efficient at large-scale decontamination. But if you don't have the resources to afford or access VHP, microwave-steam is a very easy and effective alternative. (6/8) https://t.co/cns2H1hRs0

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#7

All supplies should be universally available. We tested microwaves with multiple wattages and results were unaffected. A glass container with large surface area and a mesh are all you need.

We emphasize that N95 reuse should be a last resort. Use new ones if available. (7/8)

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

#8

See our preprint here. Please reach out to us if you have comments or questions! We are grateful to the Kirby lab at BIDMC for hosting us (@alex_nguyen_ba, @DvirReif, and me). And special thanks to @baym and @implosian for help with strains! (8/8)
https://t.co/QtNpxb4IN1

¡ª Tanush Jagdish (@TanushJagdish) April 26, 2020

"We applied about 10 million live MS2 viruses on different regions of N95 masks. Microwaving this mask on a wide glass container (17 by 17 cm) containing 60 mL water for 3 minutes eliminated close to all viruses. An average of 99.9999% or 6log reduction," he wrote.

"The idea is that steam generated from container is sufficient to permeate mask membranes and kill close to all 10 million viruses. Using any microwave-safe mesh should work. We used easily available plastic meshes that come with clementines and oranges," he explained on Twitter.

Jagdish believes that the method could be of much use in India. He said that complicated and time-consuming methods like VHP decontamination are unlikely to be useful across many parts of India if N95s or other PPEs become short-of-supply in future.