Written by: Yuzuru Anzai, M.D.
Dr. Anzai is a past president of JMSA. He is an attending at Lenox Hill Hospital and President, New York Midtown OBGYN
Why is the ventilator so important?
You must have heard Governor Cuomo repeating the shortage of ventilator so many times during his daily briefing. Why is this medical device so important?
The lungs are responsible for gas exchange-removing CO2 and supplying oxygen. This exchange takes place at alveoli, tiny balloon-shaped sacs at the end of the respiratory tree. Novel coronavirus (SARS-CoV-2) infections cause inflammation of this tissue and impair gas exchange. When the inflammation is severe, it results in ARDS (Acute Respiratory Distress Syndrome). It leads to hypoxia of the tissues and causes multi-organ damage. These patients are prone to rapid decline of their condition, requiring respiratory support through a ventilator. Ventilators allow the delivery of high pressure oxygen at high concentrations. To avoid sudden deterioration, intubation tends to happen sooner in COVID patients.
With general pneumonia, patients on a ventilator would receive antibiotics to treat their infection, and once their lung condition improves they can be extubated. However there is no established treatment for SARS-CoV-2 infection. Therefore the patients with COVID tend to stay intubated for a longer period of time. Even with this life support, many patients unfortunately cannot recover and die. According to reports from the UK (probably the largest at this point) and US, 2/3 of patients on ventilators die. The significant part of remaining 1/3 include the patients who are alive under treatment, indicating that the mortality of this of group may be higher. (INARC report on COVID-19 in critical care April 4 2020) While ventilators are essential in the treatment of COVID-19, they are not enough and we desperately need something else to treat the infection itself.
What is the fatality rate of COVID?
As you know there is no straight forward answer to this question. Worldwide it is about 6%, in US 3%, Italy 13%, and Germany is less than 2%. Japan is also around 2% at this point. However it depends on how many infected patients are identified. The more tests you perform, the more infected people you will find, many of whom can be asymptomatic. By expanding the tests, you will lower the fatality. If you limit the tests, you may artificially inflate the fatality rate. The other factor can be the age distribution of the people who are affected. In Germany, more young people have been infected who tend to do better, whereas in Italy, more older people have been infected, resulting in a higher number of deaths. Also, the Wall Street Journal reported that in Italy many people who died at home without a confirmed diagnosis of COVID were not included in the statistics, so the real fatality is probably higher (Probably the same in Wuhan, China. ) Of course if there are more patients than the hospital can handle, it will lead to a higher number of deaths, a situation the US is working very hard to avoid with seemingly positive results so far.
If we can measure antibodies against SARS-CoV-2 in blood, we can identify people who had an infection even without symptoms, leading to more accurate statistics. It may prove that fatality rates are much lower by screening larger population and identifying those who had been exposed( In this case denominator will be much larger). These antibodies may also indicate immunity to this virus and people who have it may be less likely to get infected in the future.
I read that tests are available in other countries. A few days ago, it was reported that the FDA approved antibody testing of COVID. Apparently this was not entirely accurate as described in the email from NYC department of Health. FDA has not reviewed the tests and has not approved it. While they are not objecting the development and distribution of the tests, they say these tests cannot be used alone to establish or exclude the diagnosis of COVID-19 and also positive antibody may indicate the exposure to other types of coronaviruses.
Is the mask effective?
On April 4, the CDC issued the recommendation for the general public to wear masks. Because of the shortage of masks even among health care professionals, they advise using even home- made mask and include instructions on how to make them.
It is believed that masks may prevent spreading the infection if infected individuals wear them because they may block droplets containing viruses. But fine aerosolized viral particles are too small and can penetrate regular masks, thus failing to provide protection to the people wearing them. However, since so many people are infected and up to 50% of them are asymptomatic (CNN reported the data from Iceland), if everyone wears a mask, it may protect everyone.
There are some scientific evidence to support the use of mask. In Nature Medicine (4/3/2020) Dr. Leung’s group reported that surgical mask effectively blocked aerosolized coronaviruses in exhaled breath. At the same time Dr. Bae and colleagues published a letter in Annals of Internal Medicine on 4/6/2020 that regular surgical masks cannot keep the virus in when the patients cough as they could detect virus particles outside the mask. However, they do say that it may prevent the virus from traveling further. Therefore, this finding cannot say that masks are ineffective.
I have to say I do not like wearing masks. But with pandemic of COVID-19, it is everyone’s responsibility to wear a mask, not to protect yourself, but to protect others.
Can pets transmit novel coronavirus?
On 4/6, it was reported that a tiger in the Bronx Zoo tested positive for COVID. This brought some anxiety to pet owners. Can their pet get infected or transmit the infection? The New York Times reported on this topic. Apparently, there was an experiment in which they made house cats inhale SARS-CoV-2 but the cats did not get show similar symptoms. However a new report in Journal Science said viral replication was observed in cats and ferrets are susceptible to infection whereas SARS-CoV-2 replicated poorly in dogs, and not in chickens, pigs and ducks. (Shi et.al Science 4/8/2020) I also read that SARS (close to the virus causing Covid-19) was transmitted from bats through civets (they are sometimes called civet cats but they are not cats) in China that people eat, thus is not applicable to normal house pets. The New York Times says it is unlikely that you can get infected from your pets but to exercise the same kind of precautions (even though you cannot expect social distancing from your pets.) It is a mystery how the tiger could get infected but the article did not touch upon it.