China is the third largest country in the world by area and the largest country in the world by population. Properly known as the People’s Republic of China, the political territory of the country includes the former nations of Tibet and Hong Kong. The capital is Beijing.
India, officially the Republic of India, is a country in South Asia. It is the second-most populous country, the seventh-largest country by land area, and the most populous democracy in the world. New Delhi is the capital.
It has an exceptionally diverse population, with Hindus, Muslims, Christians, Sikhs, Buddhists, Jains and other religions speaking over 21 recognised languages.
Russia, or the Russian Federation, is a transcontinental country located in Eastern Europe and Northern Asia. It extends from the Baltic Sea in the west to the Pacific Ocean in the east, and from the Arctic Ocean in the north to the Black Sea and the Caspian Sea in the south.
Russia spans more than one-eighth of the Earth’s inhabited land area, stretching eleven time zones, and bordering 16 sovereign nations. Moscow is the country’s capital.
The Soviet Union was dissolved in 1991 and since 1993 Russia been governed as a federal semi-presidential republic. Russia is a major great power, with the world’s second-most powerful military, and the fourth-highest military expenditure. As a recognised nuclear-weapon state, the country possesses the world’s largest stockpile of nuclear weapons.
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins.