Covid 19 Morbidity and Case Fatality Rate: An Analysis of Possible Confounding Factors

Introduction: When the first report appeared of a protective effect of universal BCG vaccination on COVID- 19 morbidity and case fatality rates, as well as referring to previous papers on the nonspecific protective effects of BCG, our interest was raised, because Mozambique was in an unusual position in relation to BCG vaccination. Based on our knowledge of the history of global public health, we constructed a table with the number of cases of COVID-19 per 100,000 inhabitants and the case fatality rate of the countries that had carried out universal BCG vaccination for a long period (India, Japan and the ex-USSR countries), compared to countries without a universal BCG vaccination programme. We found that countries that had carried out universal BCG vaccination for a long period had much lower case/population ratios and case fatality rates than those without a universal BCG vaccination programme. This exercise was repeated three times, during the month of April, with consistent results. These results made us take the decision to undertake a study of possible confounding factors Mozambique became independent in June 1975, and immediately after carried out a mass vaccination campaign with the six antigens of the recently created EPI. Smallpox vaccine was added, in order to consolidate smallpox eradication. WHO, at that time, was against vaccination campaigns, but an exceptional agreement was obtained. The campaign took place from the north to the south of the country, from February 1976 to January 1978. Every province started a routine EPI programme as soon as the campaign finished. In the campaign, all children 15 years old or younger received BCG vaccine. The coverage rate in the campaign was 97%, with 99% in the capital city of Maputo. Subsequently, the coverage rate of BCG vaccination at birth in the EPI has been always remarkably high in urban areas. In rural areas, coverage has been irregular, but has been at least 80% in the past 25 years. Therefore, most of the urban population aged 58 or less has received BCG, and so has an important part of the rural population. Such a high coverage of BCG is exceedingly rare in the world.