What counts as sero +ve Dengue for the purpose of the vaccine? Ig M, Ig G, NS1, PCR +ve? Also is there any indication that one needs a booster later on (e.g. after 6 yrs)? If the patient has fever, and low platelets, and NS1 or Ig M was +ve, is this patient eligible for vaccination 6 mths later?

Dengue history must be based on a recorded laboratory confirmation of past acute infection, which could have been tested at the time of infection by a direct diagnostic method such as polymerase chain reaction (PCR) or NS1 antigen to detect (part of) the virus or using an indirect diagnostic method such as dengue-specific serology to detect anti-dengue antibodies by ELISA or an RDT (WHO WER, 2018).

A booster dose of Dengvaxia® is not recommended. although existing clinical data on a booster dose of Dengvaxia® did not show any deleterious impact in terms of the immune or safety profile, the absence of any meaningful impact on the humoral response did not support an additional benefit of a booster dose. Therefore we do not recommend a booster dose in seropositive patients at this time.