Category: Covid 19

Los Angeles County is now the second county to show that the number of people actually infected with Covid 19 is much, much higher than previously expected.  This is very good news.  It means that most of the people who were infected with virus had no or mild symptoms.  They only found out they were infected after the antibody test. Covid 19 Tests: What we can and can’t say.

Yesterday, I wrote about a Stanford study of 3300 people of Santa Clara County that found the actual number of people infected with Covid 19 was between 49000 and 81000 people.  This is 50 to 80 times higher than the 1820 of confirmed cases reported.  This was one of the first areas in the US to report antibody testing that can indicate if the person was ever infected by Covid 19 (whether the person knew it or not).  If this trend continues, the fatality rate will much, much lower than expected. Covid 19. How many people are actually infected? Santa Clara County

Today, researchers at USC and the Los Angeles County Department of Health released results from a study of people in Los Angeles County. Their results show that approximately 4.1% (2.8-5.6) of the adult population had the antibody for Covid 19 indicating that they had been infected.  This translates to between 221000 and 442000 have been infected.  Currently, there are 7994 confirmed Covid 19 cases reported for LA County.  This means that the actual number of people who were infected is 28 to 55 times higher than previously known.  This makes the fatality rate between .2 and .3% – much lower than the 3-5% number based on confirmed cases alone.

This is now the 4^th report of larger scale antibody testing along with, Santa Clara County, California, Robbi Italy, and Gangelt, Germany.  In every case, the number of people  who were infected was 25-80 times higher than previously thought.  This has several implications.  One is the question of how effective sheltering in place was.  With only 8000 cases confirmed (before this study) it appeared that sheltering in place was very effective in a county with nearly 10 million people in it.  However, if several hundred thousand got infected anyway, the effectiveness of sheltering in place must be examined.  The second possible implication is that Covid 19 is not 10x more deadly than the seasonal flu.

These are only 4 specific areas, but the results are amazingly similar.  This is overall great news.  It means that the vast majority of people who are infected have no or minor symptoms.  It does not take away from the sadness and loss of the thousands of people who died from the virus, but it does place a different perspective on the disease that is very different from just a month ago.

A key unknown is how the presence of antibody corresponds with actual immunity from further infection.  It is not known if someone with the antibody is immune or how long the immunity lasts.

The world wide research is amazing.  However, read carefully as not all studies are rigorously and the limitation of each study are not always publicized.  The Stanford and USC studies just represent the very tip of the research iceberg on antibody testing.

In the meantime, keeping social distancing and washing your hands often remain good practices regardless of what these research studies report.

 

One of the key questions that remains unanswered about Covid 19 is how many people have actually been infected.  To date, most of the people tested have had some kind of symptom.  More recently, there have been more asymptomatic patients tested but the results are still pretty sparse.  The issue is tha fatality rate (the number of people who die if they get infected) will be greatly overestimated if large numbers of patients have no or only mild symptoms.  Some have speculated that at the number of people who are infected and don’t know it are many times higher than the number that have actually tested positive.  It is hoped in the coming weeks, when antibody tests can be given to large populations with and without symptoms, the actual number of infected people will be known.  See yesterdays blog about testing for an over view of antibody testing.    Covid 19 Tests: What we can and can’t say.

In the mean time, Stanford researchers reported doing this type of antibody screening in Santa Clara County.  In this test, the researchers chose 3300 Santa Clara residents that were representative of the residents of Santa Clara County.  At the time of this study, Santa Clara County had the largest number of confirmedcases of any county in Northern California (1,094). The county also had several of the earliest known cases of COVID-19 in the state -including one of the first presumed cases of community-acquired disease -making it an especially appropriate location to test a population-level sample for the presence of active and past infections.  Today (April 20, 2020) there have been 1820 Covid 19 cases reported in Santa Clara County.

They measured both the IgG and IgM antibodies which are indications of recent and earlier infections.  The prevalence (percentage of people who have the disease at the time of the study) was between 2.5 and 4.2%.  The population of Santa Clara County is 1.93 million people, so this would indicate 48250 to 81060 people were actually infected.  As there have been 73 deaths attributed to Covid 19, this new value makes the fatality rate .097 to .10 % – the same as for the seasonal flu.

Of course, it remains to be seen what the data looks like in a bigger area and across the US.  However, it is interesting to note that similar antibody studies in Europe (where asymptomatic people are tested as well) have shown the prevalence of Covid 19 in Robbio, Italy to be 10% and 14% in Gangelt, Italy.  This would suggest that the fatality rates in these area are also in the range of the seasonal flu.

Again, this is NOT downplaying the devastation of Covid 19 – but rather that although Covid 19 appears to be more contagious, the actual fatality rate hopefully, may not be very different from the seasonal flu.  There are currently 41575 deaths due to Covid 19 (18776 (45%) in NY alone).

It is reminded that in 2017 flu season, 44 million people got the flu in the US with 61000 deaths (1.3% fatality) so comparing Covid 19 to the flu does not diminish the terrible losses caused by the disease. 

One of the benefits of increased antibody testing that actual numbers for the disease will become known and it will better inform us on how to make health care decisions.  The good news continues to be that we, as a country, seems to have ‘stabilized’ as hospitilization rates have decreased everywhere.  NY continues to drive our nation wide statistics.  Your local area is likely not to be as bad as NY.  This and other data should guide the reopening of business and life.

You can read theentire Stanford paper at:  https://www.medrxiv.org/content/10.1101/2020.04.14.20062463v1.full.pdf

 

As we are half way through the month long national ‘lockdown’, attention is being focused on how we should return to life where we can leave our homes, go to work, shop etc.  One of the complications in deciding is the large differences between how the disease has impacted each state and that not all states have the same Covid 19 policies.  This is a discussion over 7 states.

There are 7 states that do NOT have a mandatory state wide ‘stay at home’ order.  These states are Iowa, Nebraska, North Dakota, South Dakota, Utah and Wyoming.  This does not mean there are no restrictions, but it means that the Governors or Legislaturs have not issued a mandatory stay at home or business shut down order.  Each state does have ‘mitigation’ policies such as closing schools and universities, and social distancing and testing programs.  Each state allows each city or county to add additional restrictions if they feel it is in their best interest.  The policy is to allow the most local government to make the decision that they feel is best for them.  In each state, there are cities are counties that have instituted a ‘shut down’ of all nonessential businesses, but the shut downs are not statewide.  There have been some areas which have placed limitations such as the maximum number of people in a store and other restrictions, but the restrictions are local.

To date, these states are 7 of the 16 states with the lowest number of Covid 19 deaths/million people.  Of these states, Iowa has the most deaths/million with 14.  It should be noted that 9 of these 14 deaths in Iowa were in one living facility.  Wyoming has the fewest deaths of any state with 1 attiributed to Covid 19.

Overall, the average statistics for these 7 states are far better than the national average:  There are fewer cases/million and fewer deaths/million.

Cases/million (average)

7 states: 598           50 states: 1410

Deaths/million (average)

7 states: 8           50 states: 51

It should be noted that the average death rate for the 50 states is dominated by results from 6 states which have over 124 deaths/million (NY 513 to Mass 124 deaths/million).  If you exclude these, the national average is 25 deaths/million.  In either case, the 7 no lockdown states have significantly lower death rates.

It is interesting to note that these states have been very aggressive in testing.

Tests/million

7 States: 9807         50 State: 9936

Utah and North Dakota are in the top 10 states with the most testing/million

The population of these states represent less than 3% of the US population.  However, these states seem to fair better than other states with similar populations.  Utah and Iowa have the largest populations of the 7 state with populations of about 3.2 million.  Some States with comparable or lower populations have significantly higher cases and deaths/million.

State	Population	Cases/million	Deaths/million
Nevada	3.1	1026	41
Mississippi	2.98	884	33
Kansas	2.91	473	21
Rhode Island	1.08	2817	69
Delaware	.97	1855	43
Vermont	.62	1197	45
Wash DC	.73	2856	76

Only time will tell if these 7 states made the right decision.  However, it does illustrate clearly that not all states have the same distribution of Covid 19 cases and deaths.  They are, on average, less socially distanced as many businesses remain open in these states.  If we could develop a better understanding of why the number of cases and deaths are low in these 7 states that did not lockdown, perhaps it will give insight into how to reopen the country in the other states.

There are couple of possibilities.  The good possibility is that a high number of people in these states have actually been infected but the infections have not resulted in a high number of deaths.  If this is the case, then a large population of these states are being immunized (herd immunization) and there will not be a spike in the number of infections.

The bad possibility is that unknown factors have delayed the onset of the infection and that infection and death rates will climb.  However, the numbers are so much better than the other states, that the situation would have deteriorate rapidly to reach the same levels.

This illustrates the complexity of decision making.  When the restrictions are lifted on businesses and people are free to go about, what policies should be instituted, when should they be instituted, do you institute the same policies everywhere?  Based on current information, different areas of the country differ greatly in the number of cases and number of deaths.