* What are the factors that have led to the spread of this pandemic (origin-Wuhan)?
Answers
Answer:
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Explanation:
the factors are : . Endemicity for other infections
Taking Brazil as a thermometer, this country has been dealing with important seasonal outbreaks of virus infections such as dengue, zika, chikungunya, and yellow fever. In Brazil more than 350′000 dengue cumulative cases have been reported since starting of this year. Therefore, it is important to consider this region as primed for these infections: Reconvalescent people keep some level of immunity as memory Cytotoxic CD8+ T and or antibody producing Plasma B cells. Moreover, it has been shown that cross immunity is active in Flavivirus infections [2]. Even though the coronaviruses belong to another family, they may conserve some immunogenic epitopes. In murine models, prior immunity to distinct Flavivirus can somehow be protective to secondary challenges with other counterparts. In humans it is controversial if this cross immunity is beneficial or not. In the current outbreak it is difficult to analyze whether those levels of anti-Flavivirus antibodies and/or specific T-cells could cause a more severe or a mild disease. One way to address this question will be with cross-sectional studies comparing prevalence of antibody titers against many of those infections, with anti-SARS-CoV2, and also disease severity in different populations.
2. Immune regulation with other co-infections
The immune response against virus infections is usually Type I and it acts to clear the virus and virus-infected cells. It has been long known that in murine models Type I response is counterbalanced and inhibited by Type II response which is more directed against helminths. It was recently demonstrated in a murine model that the efficacy of vaccination against seasonal flu is impaired by concomitant helminth infection in an IL-10 dependent manner.