As mentioned above, petechial fever is quite dangerous even though we have treatment for it. If you have a petechial fever, the worst scenario is that you would end up hospitalized. The mosquito sucks your blood to nourish her eggs and our trip sadly ended earlier than expected. A mosquito net will protect you from this bloodsucker.
Some tourists prefer to soak up the sun but in Hanoi, Vietnam, the hot season is so extreme that many people get sunstroke. Do not underestimate this problem! Also, without umbrellas or raincoats, you may get soaked to the skin due to sudden showers.
If your immunity is weak, it makes sense anyway that you are ill, have to lie on your bed, take some pills and stare dejectedly out the window. A sense of disappointment arises, for sure.
Weighing up all the pros and cons, Metta Voyage highly recommends tourists visit Hanoi during the dry season (November to April) for the sake of your exhilarating and unforgettable experience.