The main feature of double-needle vaccine is that it needs two shots, and the two shots need to be shot at a certain interval, so the protection efficiency is not so high. A single shot vaccine only needs to be injected once. After 28 days of injection, the protection efficiency of critically ill patients was 100%, and the overall protection efficiency was about 70%. Moreover, the biggest advantage of single-needle vaccine and double-needle vaccine is that they will not cause serious adverse reactions, and they are inactivated vaccines.
These two COVID-19 vaccines have different protective mechanisms. The protective mechanism of double-needle COVID-19 vaccine may not be obvious in a short time, but its durability in the future is better than that of single-needle vaccine.
However, some people have raised some questions, why a double-needle vaccine was developed within one year after the outbreak of the COVID-19 epidemic, but a single-needle vaccine has not yet been developed, because the double-needle vaccine is used in an emergency. The research and development of single-needle vaccine is well controlled in China, and there is enough time to verify its stability and whether it will cause adverse reactions. Moreover, a single-needle vaccine needs to cooperate with some people abroad, so time and efficiency still need to be synchronized.
It takes time to test the safety and effectiveness of these COVID-19 vaccines, because this is a medical experiment, not a real science. But after such a long trial, inactivated vaccine is the safest and most stable.
This also shows that China is a superpower and can deal with emergencies well. Moreover, in this epidemic war, it shows that the people of China can overcome all kinds of difficulties as long as they unite as one, and China has also provided help to many countries, showing the attitude that a big country should have.