Covid-19 update

Another week, another set of updates! Here we go:

1.  Moderna, the Cambridge based biotech firm working on a novel mRNA vaccine announced that volunteers who received their vaccine mounted an antibody response. Forty-five people received the vaccine, and the level of antibodies was the same or higher than the levels seen in people who have recovered naturally from a Covid-19 infection. They then harvested the antibodies from 8 of those patients and showed that in the lab they had activity against Covid-19. Moderna is planning a Phase 2 trial with 600 patients, and a larger Phase 3 roll-out this summer. In general, Phase 1 assesses safety in a small number of persons. Phase 2 continues to look at safety and also looks for efficacy, and Phase 3 is a larger trial looking for greater confidence in efficacy and evidence of any unintended side effects. Moderna, which has never produced a vaccine or any drug for that matter, has an arrangement with the Swiss company Lonza to manufacture 1 billion doses per year starting in July 2020. An mRNA vaccine has never been created in history, so this represents one of the largest scientific gambles in history.
2.  Can dogs sniff out Covid-19? The phenomenon of dogs and some people for that matter being able to smell certain diseases is not new. Last year in England, a woman learned through chance that she had the strange ability to smell people who had Parkinson’s Disease and even stranger, she could detect persons who had not yet developed Parkinson’s. We know dogs’ noses are hundreds of times more sensitive than ours, but their communication skills are not quite as developed. Charity Medical Detection Dogs, based in Milton Keynes which is northwest of London, is working with the London School of Hygiene and Tropical Medicine and Durham University on the project. They have already proven that dogs can detect the smell of patients with malaria and some cancers. Their goal is to train dogs to detect the smell of people with asymptomatic Covid-19 infections in order to get them tested and quarantined before they infect others.
3.  Who’s already had it? Of course, this varies widely by geography, even within one state or one county. And the degrees of testing also vary widely. From April 27 to May 8, 750 asymptomatic people from three Boston neighborhoods were tested for antibodies to and active infection with Covid-19 in a study run by Mass General Hospital and the Boston Public Health Commission. Only 10% had antibodies, suggesting that approximately 90% of the population remained still vulnerable to the infection. The median age of this cohort was 42. The highest percentage of people with antibodies was 13.3% in East Boston, and the highest percentage of active infection was 4.6% in an area of Dorchester. The overall rate of active infection was 2.6% in persons who did not recall being sick. The overall antibody rate of 9.9% is far lower than the 31% of antibodies found in asymptomatic residents of Chelsea – the hottest spot in Massachusetts. In another study, 16 of 224 municipal workers in Brookline, or 7%, tested positive for antibodies. Just as a reminder, we are not really safe until 70-80% of the population has antibodies, or we have an effective vaccine or medical treatments.
4.  Stats on Risks A recent article titled, The Risks – Know Them – Avoid Them by Professor Erin Bromage at U. Mass Dartmouth, put some numbers to the varying types of risk of infection with different exposures. Here are some of the key takeaways:

•  Based on research previously with SARS, it is estimated that infection can take hold if someone inhales at least 1,000 viral particles.
• 1,000 Covid-19 particles could infect someone with one eye rub, or one breath of 1,000 particles or 10 breaths of 100 particles each.
• A single cough releases about 3,000 droplets, and droplets travels at 50 miles per hour. Most droplets are large, and fall quickly (gravity), but many do stay in the air and can travel across a room in a few seconds.
• A single sneeze releases about 30,000 droplets, with droplets traveling at up to 200 miles per hour. Most droplets are small and travel great distances -- easily across a room.
• If a person is infected, the droplets in a single cough or sneeze may contain as many as two hundred million virus particles which can all be dispersed into the environment around them.
• A single breath releases 50 - 5000 droplets. Most of these droplets are low velocity and fall to the ground quickly. There are even fewer droplets released through nose-breathing. Importantly, due to the lack of exhalation force with a breath, viral particles from the lower respiratory areas are not expelled. Unlike sneezing and coughing which release huge amounts of viral material, the respiratory droplets released from breathing only contain low levels of virus.
• We know that at least 44% of all infections--and the majority of community-acquired transmissions--occur from people without any symptoms (asymptomatic or pre-symptomatic people). You can be shedding the virus into the environment for up to 5 days before symptoms begin.
• Successful Infection = Exposure to Virus x Time
• Any environment that is enclosed, with poor air circulation and high density of people, spells trouble.
• Example: An outbreak in a call center. A single infected employee came to work on the 11th floor of a building. That floor had 216 employees. Over the period of a week, 94 of those people became infected.
• The main sources for infection are home, workplace, public transport, social gatherings, and restaurants. This accounts for 90% of all transmission events. In contrast, outbreaks spread from shopping appear to be responsible for a small percentage of traced infections.
• Social distancing guidelines don't work well in indoor spaces where you spend a lot of time, as people on the opposite side of the room were infected.

Many of my comments over the past number of weeks have focused on the importance of person to person transmission via respiratory droplets. This week the CDC changed its guidance to further emphasize the magnitude of person to person respiratory transmission over the chance of touching an infected surface.

5.  Can you get it again? A study just published in the journal Science by Dr. Dan Barouch at my former employer, Beth Israel Deaconess Medical Center in Boston, sheds some important light on this subject. In the first study they infected nine monkeys with Covid-19. All the monkeys developed viral pneumonia and then recovered. One week later, they reinfected all nine monkeys, but none of the animals got sick the second time. This proved the immune response protected them. In a second study, they vaccinated 25 monkeys with an experimental vaccine. They then infected these 25 monkeys with Covid-19 in addition to infecting 10 monkeys that had not gotten the vaccine. None of the vaccinated monkeys got high levels of virus in their lungs, but all of the unvaccinated monkeys did get high levels of virus. The so-called DNA vaccine used in this study is one of over 100 experimental vaccines being developed around the world.