A Blog by Pierre Lutgen in the MalariaWorld Newsletter (https://malariaworld.org/search/site/Malaria%20inhibits%20Covid) refers to the high overall Immunoglobulin E (IgE) levels that have been found in human populations in areas where malaria is endemic. Further to what is explained in his Blog, but on a different subject:
One of the reasons for IgE production (e.g. Fincham et al., 2007) in malaria-endemic regions is the frequent high prevalence of infection by parasitic worms amongst people living there (e.g. Markus & Fincham, 2000; Markus, 2003). IgE is a marker for the T Helper Cell Type 2 (Th2) immune profile that is associated with helminthiasis, characteristically together with eosinophilia (e.g. Fincham et al., 2003), as well as particular cytokines.
In the absence of deworming, this Th2 scenario can result in a diminished immune response to vaccination against various non-helminthic diseases, possibly including malaria (Markus & Fincham, 2001; Markus & Fincham, 2007).
What the situation will be in relation to future COVID-19 vaccines is currently unknown. If such vaccines do not elicit sufficient protective immunity because of helminthiasis, that will, needless to say, be a problem!
Fincham JE, Markus MB, Adams VJ et al. 2003. Association of deworming with reduced eosinophilia: implications for HIV/AIDS and co-endemic diseases. South African Journal of Science 99: 182–184.
Fincham JE, Markus MB, van der Merwe L et al. 2007. Ascaris, co-infection and allergy: the importance of analysis based on immunological variables rather than egg excretion. Transactions of the Royal Society of Tropical Medicine and Hygiene 101: 680–682.
Markus MB. 2003. Public health and vaccines – immune responses in developed versus poor countries. South African Medical Journal 93: 834–835.
Markus MB, Fincham JE. 2000. Mbeki and AIDS in Africa. Science 288: 2131.
Markus MB, Fincham JE. 2001. Helminthic infection and HIV vaccine trials. Science 291: 46–47.
Markus MB, Fincham JE. 2007. Helminthiasis, bystander diseases and vaccines: analysis of interaction. Trends in Parasitology 23: 517–519.