Each time we learn about a potential Covid vaccine, there is jubilation throughout the globe. Perhaps, the most widely and closely tracked things in the world now are the most promising vaccines. Though the Oxford-led consortium had an early advantage in the race to finding an effective vaccine for convenient mass-immunisation, now it seems that Pfizer and Moderna have overtaken them. Whoever succeeds in the race deserves our appreciation and support. Accordingly, both Pfizer and Moderna have received global plaudit. There are about a dozen potential vaccines in the final stages of testing, known as phase three. But, the initial euphoria over Pfizer and Moderna's success is unlikely to last long, particularly in the developing world. Until and unless we hear about other potential vaccines succeeding, a grim future awaits billions of people.   Vaccines developed by both Pfizer and Moderna have being described as game changers. Trial data released by Pfizer shows that the...