Covid World Update

Further information on Natural versus Vaccine Immunity.

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While Americans are celebrating what many think is the end of the pandemic, it’s hard to ignore the dramatic turn of events in many locations around the world. When the extreme degree of Omicron’s transmissibility quickly became apparent, one of the first things that ran through my head was; zero COVID policies in countries around the world are certainly doomed to failure. It didn’t take very long to see this playing out. New Zealand for instance, which only in August had put the entire country into lockdown after a single case of community transmission, is now experiencing a massive wave of infection. This week, despite a high level of vaccination, they hit 24,000 new cases a day, and hospitals are overwhelmed. Many of you have probably seen the pictures from Hong Kong of body bags stacked up in wards next to living COVID patients; they can’t transport the bodies to the morgues and refrigerated trucks fast enough. Hong Kong might officially still be obliged to follow the zero COVID policy of the mainland, but the system was completely overwhelmed by Omicron, and the highly mask friendly, financial hub of Asia now has gone, in the blink of an eye, to one of the highest death rates in the world. A surprisingly small 53% percent of people over 80 are vaccinated, so apparently distrust of vaccines cuts a wide cultural swath. On Wednesday South Korea, another model of a mask compliant society, continued to smash daily COVID cases hitting 342,000, with rapidly rising hospitalizations. China is still pursuing zero COVID, and despite draconian measures, I think they will also fail. They just locked down the capital of Jilin province, a city of 9 million, with orders that only one member of each family can leave the house once every 2 days for food or medicine. Given the miserable performance of the home grown Chinese vaccines compared to the RNA models or even Astra-Zeneca’s, they have good reason to worry.

We should ask why this is happening in these locales that previously had a good Covid track record. The trivial answer is that the virus does what it wants, and isn’t particularly concerned with a variety of human mitigation efforts. Alternatively, at times it has seemed to me that the virus seeks out hubris, and punishes it with the verve and tenacity of the Olympian Gods. I think the answer I’ll settle on is two-fold. Omicron is so much more highly transmissible that the clear benefit afforded by masks during earlier waves is largely circumvented. That certainly seems to be true for any mask less effective than N95 or KN95. The other possible explanation I would suggest, with no data to back it up, is a general relaxation in mitigation efforts due to pandemic fatigue.

Since we are on the subject of masks, briefly only, I’d like to point out the recent CDC study showing clearly that masks were effective in schools during the huge and highly deadly Delta wave. The data released this week in MMWR demonstrates that public school districts in Arkansas with mask mandates had 23% reduced rates of infection in both students and staff compared to no mandate school districts. So am I very upset that schools all over the country are dropping mask mandates on the recommendation of the CDC? The current rapidly declining case counts coupled with realization that Omicron realistically requires KN95 or better masks to make a significant impact on transmission provides the answer.

The last point of interest today is a bit of a hot-button item, so here’s your trigger warning if you want to quit while I not too far behind. The issue of natural immunity versus vaccine immunity became a virtually verboten topic last summer, largely it seems because of claims made by a prominent US senator. There were already quite a number of papers in the literature by that time showing that reinfection rates after recovery from COVID were in fact very low. There were also quite a number of immunology papers demonstrating that antibody levels shortly after vaccination were higher than those seen on average after infection. Now antibody levels and T cell activity in the lab are one thing, but how many people actually come down with the disease in the real world is the gold standard. Giving careful consideration to the strong possibility that natural immunity might be as good, or perhaps even better than vaccine induced immunity was seen as subversive and cast you into the camp of the know-nothing senator and the anti-vaxer crowd.

Just out in preprint form this week is the first large scale synthesis of results from a number of high quality clinical studies addressing the issue of the efficacy of natural versus vaccine immunity. Importantly, it also looks at the issue of how effective is vaccination of previously infected people.

https://www.medrxiv.org/content/10.1101/2021.09.12.21263461v1

Across all studies they found natural immunity was at least equivalent to vaccination, and in four of the nine studies it was superior. They also found an extremely modest benefit of vaccination following recovery to no vaccination. In that circumstance, they calculated that you would need to vaccinate 218 convalescent individuals to prevent 1 COVID infection per year. Vaccinating recovered people was 33.5 times less effective in disease prevention than vaccinating naives. That really surprised me. Why should anyone care about all this and risk the opprobrium of blurting these statistics out at a particularly boring cocktail party? Well it is profoundly important in terms of vaccine mandates, including the Federal mandate, which fail to take this into account. It is also an important bit of data if you are weighing the question of taking another dose of vaccine after recovering from Omicron. Finally, for the altruistically minded, you might find it unsettling that the first world may be overdosing itself with extra doses of vaccine that will have little to no effect, while a large segment of the world is still unvaccinated and not through choice.