The worldwide situation of the COVID-19 pandemic may reach a turning point in June or July as mass populations are vaccinated against the virus, a leading expert in Shanghai said.

"International travels at a relatively large scale may restart at the end of this year when vaccinations play their part among the population," said Zhang Wenhong, leader of the Shanghai team of experts in the clinical treatment of novel coronavirus pneumonia cases, during an exclusive interview with People's Daily published on Friday.

"But when the number of flights increases, even if everybody boarding the flights holds a nucleic acid test or vaccine injection report, it doesn't mean that the number of imported cases will drop sharply soon. We'll see a gradual process in the decrease," said Zhang, who also is director of the Department of Infectious Diseases at Huashan Hospital Affiliated with Fudan University in Shanghai.

Zhang, who took the COVID-19 vaccine on Dec 31, said China also needs to popularize the vaccines to the mass public.

In the long run, vaccines, rather than quarantine or home isolation, are the key to any country's strategy of epidemic prevention and control, he said.

He noted a COVID-19 vaccine product with a protective rate between 60 percent and 70 percent or above is eligible for mass use. The coverage rate of vaccines among the entire population is more important than the protective rate for individuals, he said.

"Key groups of individuals are strongly urged to receive the vaccines and we believe the virus' spread will be effectively crippled when the coverage rate of the vaccines among the entire population reaches 70 percent," Zhang said.

One of the key groups are frontline workers dealing with cargo at customs and airports as they are faced with high risks from imported cargo and cold-chain transportation.

People with a higher mortality rate after contracting the virus, such as the elderly, are another key group, Zhang said.