The WHO announced yesterday that there is not sufficient evidence to conclude that someone who has recovered from the corona virus has any immunity to getting that disease again. The announcement made big headlines, but what really happened here?
Let's start with what we know:
1. Essentially every virus in the past has resulted in recovered patients getting some level of immunity to re-infection.
2. The length of immunity varies. Sometimes the immunity is permanent. For example, chicken pox is caused by a virus and confers permanent immunity. Of course, people who have had chicken pox can still get shingles years later from the same virus. Some immunities are for a period of many years. Here a good example is smallpox. The vaccine causes the body to develop the immunities that protect it, but those immunities are only good for 10-20 years. Other viruses convey much shorter immunity periods. Influenza is a good example. Just because one had the flu last year does not mean one is immune to getting it again next year. In part that is due to the fact that there are so many different strains of the flu virus, but the immunity conveyed from an infection is also one that just doesn't last for years.
3. There have been a few cases in which people who recovered from corona virus then tested positive for the disease shortly thereafter. Does this mean these people are not immune? Most likely, the answer is NO. In most cases, the initial test that showed the patient no longer having the virus was probably giving a false negative. A faulty test result declared the patient recovered followed by another correct test that says the patient is infected. There also could be faulty tests that declared the patient re-infected.
4. There are many hundreds of thousands of people around the world who have recovered from the corona virus. To date, there are no examples of anyone who recovered testing positive again many weeks later. Testing positive within a week of "recovery" is probably just an indication of a faulty test for the recovery or the new infection. Testing positive many weeks after recovery would indicate a reinfection. Those positive results many weeks later is what is not being observed.
Since there are no instances of people testing positive many weeks after have been designated recovered, that's a pretty good indicator that recovery conveys immunity to the patient. We just don't know for how long that immunity lasts.
So why would the WHO issue this warning? If you want to think about it from a scientific standpoint, all the WHO is saying is that there is not yet sufficient evidence to conclude that infection and recovery conveys any immunity to reinfection. The WHO isn't saying that such immunity is not being given to recovered patients; WHO is only saying that there isn't enough information yet to make a scientific conclusion one way or the other.
On the other hand, if you want a political reason, then you need to think about who benefits from this announcement. China, for one, is already proceeding with full opening of its economy without concern regarding possible reinfection. That will not stop no matter what the WHO says on this subject. On the other hand, countries like the USA and those in the EU that have not reopened in a major way could slow down that reopening due to concern over the latest WHO announcement. That would give China an advantage. It would be going full speed ahead while its rivals in other countries are still shut down. If, as has been alleged, the WHO is really following directives from China, then this announcement makes sense.
There's no way to know right now why WHO made the announcement. It would be foolish, however, for policy makers to conclude that there is no short term immunity conveyed by the disease. Given that we have half a million or more documented recovered patients and there have yet to be any who got reinfected many weeks later, it seems almost certain that these recovered patients have immunity.
Let's start with what we know:
1. Essentially every virus in the past has resulted in recovered patients getting some level of immunity to re-infection.
2. The length of immunity varies. Sometimes the immunity is permanent. For example, chicken pox is caused by a virus and confers permanent immunity. Of course, people who have had chicken pox can still get shingles years later from the same virus. Some immunities are for a period of many years. Here a good example is smallpox. The vaccine causes the body to develop the immunities that protect it, but those immunities are only good for 10-20 years. Other viruses convey much shorter immunity periods. Influenza is a good example. Just because one had the flu last year does not mean one is immune to getting it again next year. In part that is due to the fact that there are so many different strains of the flu virus, but the immunity conveyed from an infection is also one that just doesn't last for years.
3. There have been a few cases in which people who recovered from corona virus then tested positive for the disease shortly thereafter. Does this mean these people are not immune? Most likely, the answer is NO. In most cases, the initial test that showed the patient no longer having the virus was probably giving a false negative. A faulty test result declared the patient recovered followed by another correct test that says the patient is infected. There also could be faulty tests that declared the patient re-infected.
4. There are many hundreds of thousands of people around the world who have recovered from the corona virus. To date, there are no examples of anyone who recovered testing positive again many weeks later. Testing positive within a week of "recovery" is probably just an indication of a faulty test for the recovery or the new infection. Testing positive many weeks after recovery would indicate a reinfection. Those positive results many weeks later is what is not being observed.
Since there are no instances of people testing positive many weeks after have been designated recovered, that's a pretty good indicator that recovery conveys immunity to the patient. We just don't know for how long that immunity lasts.
So why would the WHO issue this warning? If you want to think about it from a scientific standpoint, all the WHO is saying is that there is not yet sufficient evidence to conclude that infection and recovery conveys any immunity to reinfection. The WHO isn't saying that such immunity is not being given to recovered patients; WHO is only saying that there isn't enough information yet to make a scientific conclusion one way or the other.
On the other hand, if you want a political reason, then you need to think about who benefits from this announcement. China, for one, is already proceeding with full opening of its economy without concern regarding possible reinfection. That will not stop no matter what the WHO says on this subject. On the other hand, countries like the USA and those in the EU that have not reopened in a major way could slow down that reopening due to concern over the latest WHO announcement. That would give China an advantage. It would be going full speed ahead while its rivals in other countries are still shut down. If, as has been alleged, the WHO is really following directives from China, then this announcement makes sense.
There's no way to know right now why WHO made the announcement. It would be foolish, however, for policy makers to conclude that there is no short term immunity conveyed by the disease. Given that we have half a million or more documented recovered patients and there have yet to be any who got reinfected many weeks later, it seems almost certain that these recovered patients have immunity.
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