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Feature Coronavirus

Covid-19: Do many people have pre-existing immunity?

BMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m3563 (Published 17 September 2020) Cite this as: BMJ 2020;370:m3563

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Covid-19 immunity, covid vaccines, and influenza vaccines

Dear Editor

The possibility that population immunity to Covid-19 is much higher than has been publicized and that the herd immunity threshold (HIT) could be as low as 10% comes as a revelation. (Doshi, BMJ 2020;370:m3563, Sept 17) I hope this information reaches public health authorities in the US where worst-case scenarios seem to be driving lockdowns, “warp speed” development of Covid-19 vaccines, and where fear of a “twindemic” is driving a stampede to influenza vaccine mandates—in California, Massachusetts, New Jersey, and Vermont, so far.

Influenza vaccine mandates are especially problematic. The most recent publication indicates that, when studied over several seasons, influenza vaccines are associated with increased mortality in the elderly. During six A/H3N2-predominant seasons vaccine effectiveness (VE) against all-cause mortality among elderly men was -16.6% (-32.2% to -1.1%). (Anderson et al, Ann Intern Med, 3 March 2020, Supplement Table 14) Over 14 seasons overall VE against all-cause mortality in elderly men was -8.9% (-19.6% to 1.8%). (Table 2 in Anderson et al) Furthermore, there is a strong geographic correlation between influenza vaccine uptake in the elderly and Covid-19 death rates. (www.bmj.com/content/369/bmj.m2184/rr-4) Although influenza vaccines provide modest, short term protection against circulating influenza viruses, the vaccines are consistently associated with increased risk of illness from non-influenza respiratory viruses (NIRVs). I am aware of eight studies published between 2011 and 2020 with odds ratios or hazard ratios between 1.06 and 4.91.

Six years ago Margaret McCartney asked “What use is mass flu vaccination?” and called for randomized trials. (BMJ 2014;349:g6182) A few infectious disease and public health experts have made the same demand. So far the authorities have not seen fit to comply….Recently Els Torreele warned that the rush to create a Covid-19 vaccine was likely to do more harm than good. (BMJ 2020;370:m3209, Aug 18. BMJ Opinion, Sept 16) His warning was reinforced by Fiona Godlee. (“Less haste, more Safety.” BMJ 2020;370:m3258, Aug 20) Their warnings could also apply to influenza vaccines, which I hope are heard by US authorities.

ALLAN S. CUNNINGHAM 18 September 2020

Competing interests: No competing interests

18 September 2020
Allan S. Cunningham
Retired pediatrician
Cooperstown NY 13326 USA <crabarbicus62@gmail.com