Diluting the vaccine or delaying the second dose is a reckless move, which may give SARS-CoV-2 an opportunity to mutate beyond the power and protection of our current set of vaccines.
With a limited supply of Covid-19 vaccines, the question on many minds is whether to dilute the vaccines or delay the second dose to speed Covid-19 vaccination. My answer is neither—the greatest threat to population protection is virus resistance. Diluting the vaccine or delaying the second dose is a reckless wager, which may give SARS-CoV-2 an opportunity to mutate beyond the power and protection of our current set of vaccines. Yet, despite acknowledging the risk, countries like the UK still seem intent on pursuing the option, putting each and every one of us at risk. All the vaccines currently approved require two doses administered three to four weeks apart. The first shot starts building protection and the second shot helps elevate the levels of protection the vaccine has to offer. Data on protection from a single dose of the vaccine is sparse, but we know that the concentration of protective antibodies is low after one dose of the vaccine or after two doses of diluted vaccines.
