The virus SARS-CoV-2 causes COVID-19, the pandemic that has posed overwhelming effects on the global health and is causing millions of death worldwide. The virus spreads easily, and the majority of the world's population is still vulnerable to it. Research is happening at breakneck speed for vaccine development as it would provide some protection by priming our immune systems to fight the virus. About 240 vaccines are in early development, and 40 more in clinical trials with nine already in the final stage of testing on thousands of people. Globally, most countries have reported sex-disaggregated COVID-19 data for cases, deaths or both. Notably, the data from several COVID-19 affected countries have pointed towards male-biasness of the disease, severity being two-times lower in females. In this article, we have discussed why there could a possibility for biological sex to impact vaccine efficacy for COVID-19.