Corona: are we over-reacting?

One of the most puzzling things about the dreaded virus is why it has so far not widely infected people of undeveloped countries like India and Pakistan. One common explanation is that most people in the subcontinent were vaccinated against malaria and tuberculosis (as well as smallpox and cholera) after birth, and this has immunized them against Corona as well. But then, why have twelve thousand odd Pakistanis and twenty thousand Indians so far tested positive? 

Also the  number of deaths in both countries are thought to be low because mostly old people die of the disease, and in both countries such people are only six to seven percent of the population. As yet, we have not seen dead bodies lying on the streets as in Italy and China, so should the governments in both India and Pakistan continue with the lock down? 

Among those I know, only one person so far who has tested positive (the niece of a near relative's wife). She's young, she tested positive thrice in a month, but the fourth time the result was negative. Her father, mother or brother have not been infected, which is strange, since in the U.S. and other countries, those who were in close contact with infected persons had to be hospitalized. 

Is it possible that due to the hot and humid climate in the subcontinent, the virus has lost its potency? Or perhaps there are many strains of the virus, some mild and others virulent?