The premise is that if COVID-19 infection protects at least some people from re-infection for a while, vaccination (because vaccines rarely carry out the body’s own immune response), evidence of immunity that can allow free travel, and reimbursement of many stopped economic and social activities may be possible.
Meanwhile, the US continues to fight the virus. COVID-19 spreads throughout most of the U.S. with rates too high for effective contact tracking, too high for safe personal education, and too high for robust economic recovery.
But can herd immunity result from infection of 20-30%, as some malicious academics have suggested recently – much lower than the usual estimate of 60-80% infection? Do not add up. Some communities already have an infection rate of 50% or higher – this would be impossible if herd immunity kicks in at an infection rate of 20-30%!
It is not either-or
Like other over-implications – open as well as closed companies, drops vs. aerosols – coupling immunity is a continuum, not an on-off phenomenon. As more people become immune, infection spreads more slowly. But because distribution is uneven, many communities remain vulnerable, even if a large portion of the population is infected. Herd immunity is then not a protection for everyone – even if many people are infected.
During a major COVID-19 outbreak on a fishing vessel, three people with a certain type of antibody, known as neutralizing antibodies (because they neutralize the virus in a test tube) appeared uninfected when almost everyone else on the vessel did. Before the departure of the ship, these three people and three others had positive tests for antibodies.
The other three had antibody tests that were false positive or weak positive (there is currently no way to know the difference), perhaps from mild pre-COVID-19 infection; they had no neutralizing antibodies.
Two of these three were infected on the ship. In contrast, two out of three people who neutralized anti-antibodies did not become infected. The third had low levels of PCR positivity, which may have reflected or low-level reinfection as persistent PCR positivity – a phenomenon described in some people after infection with the virus.
Long-lasting immunity?
It’s not enough to bet on your life, but it’s enough to be optimistic about the potential for natural immunity after exposure to COVID-19; more severe disease seems to correlate with more robust immune protection. The fishery outbreak study did not provide any information on symptomatic disease, as one of the 6 people who were anti-body positive prior.
Next, we need to find out how long immunity to neutralizing antibodies lasts, how complete it is, and what proportion of infected people are protected.
Now the danger. Our immune response is not all right. Developing immunity – whether through infection or vaccination – can result in serious illness. This is why some people get so sick with COVID-19, and probably why dexamethasone, a medication that weakens the immune system, helps some seriously ill patients.
And it is a concern with vaccination, which could potentially harm a small proportion of patients due to immune response – either from the vaccination itself, or by exposure to the virus after vaccination by vaccination. This is carefully examined in the faxes that are developed and will need to be followed when they are given.
Become visible
The other danger of immunity is overconfidence, which can lead individuals and communities to neglect it. If individuals or communities believe they are protected but do not, the result may be more widespread and more deadly.
In the outbreak of the fishing boat, two of the three people who tested positive for antibodies but did not receive neutralizing antibodies became infected. There is no way to know if the results of these patients were false positions as weakly positive, but the bottom line is clear: positive testing for antibodies does NOT mean you are immune. Overconfidence can kill.
In the US, those most at risk have the least access to care – this is known as the Reverse Care Act and is a sad and accurate comment on the injustice of the American health care system, with which New York City is no exception .
Crowding and herd immunity
Positivity rates of anti-anti-tests closely correlate with abundance and poverty. And while some communities may approach herd immunity because communities mingle, New York City as a community is far from herd immunity.
Getting immunity for herds in the US would require hundreds of millions of infections and at least one million more deaths. That’s not a plan – that’s a disaster.
The promise of immunity then is that neutralizing antibodies protect against reinfection. Time will tell how long protective immunity lasts and the proportion of people who need to be immune to substantially drive the spread of infection (herd immunity).
Vaccination will not be quick or easy, but it is probably possible. Now we need to develop a vaccine that is effective, safe, trusted and widely available. If a safe and effective vaccine is widely available, immunity passports can become a reality.
We can reach a new normal as we improve control today, stay apart, work together, and prepare for vaccination as and when it becomes available. For now, we need to continue wearing masks, looking at our distance and washing our hands.
Our schools and universities need to be extremely careful. In most of the country, we have to keep our bars closed, indoor dining closed, and avoid closed indoor spaces with a lot of people present. There may be light at the end of the tunnel, but immunity is definitely not just around the corner!
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