America's Surgeon General Dr Vivek Murthy on 18 July expressed concern over the "significant increase" in COVID-19 cases in the US, especially among the unvaccinated population, urging people to get vaccinated and assuring them that the current set of vaccines are highly effective against coronavirus.

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The Indian-American doctor said the vaccinated people are "highly protected" and 99.5 per cent of the deaths recorded from the COVID-19 infection are among those who are unvaccinated. This is an issue of concern especially given the Delta variant, Murthy told CNN in an interview. "What we're seeing in LA County is concerning, this rise in cases. Unfortunately, we are seeing rises particularly among the unvaccinated in many parts of the country now and especially given the Delta variant, he said.

"What the CDC did in its guidance about - close to two months ago now, is based on the science saying that your risk of getting sick or transmitting the virus was low if you were fully vaccinated. They gave communities and individuals the flexibility to make decisions about what to do with masks, he said. "I'm concerned about what we're seeing in the country right now. We are seeing increase in cases, particularly in parts of the country where the vaccination rates are low," he said. Murthy, however, said the good news was that among those who are fully vaccinated, there is still a high degree of protection, particularly from hospitalisations and deaths.

"In fact, 99.5 per cent of the deaths that we're seeing right now from COVID-19 are among those who are unvaccinated, Murthy told Fox News in another interview. So the worry that we are seeing, in fact, significant increases among the unvaccinated. But the good news is the vaccinated are still highly protected, he said.

In areas where there are low numbers of vaccinated people or where cases are rising, it' is very reasonable for counties to take more mitigation measures, like the mask rules that you see coming out in Los Angeles, he told CNN in response to a question "And I anticipate that will happen in other parts of the country, too, he said. "Should also say that for individuals, as well, depending on their circumstances, some people may choose to continue wearing masks such as those who may be immunocompromised or people who have those - family members at home who are unvaccinated. "So people can make these decisions. Counties certainly have the right to put mitigation measures back in place, and that's not contradictory to the guidance the CDC has issued, said the Indian-American surgeon general," he said.

Murthy said the current set of vaccines were highly effective against COVID-19. In the case of the mRNA vaccines, more than 90 per cent effective in preventing symptomatic infection, but they're not 100 per cent perfect, he said. No vaccine is. That means you will see some numbers of people who have breakthrough cases. But there are two things to know about that. One is that these numbers will be small, he said. So far, more than 160 million people in the US have been fully vaccinated.

So, you will see numbers, a minority, a small minority of people who do have breakthrough infections. But here's the other thing to know, is that when you're fully vaccinated, even if you do have a breakthrough infection, it's much more likely that infection will be either asymptomatic or mild. "And that's really good news that continues to tell us that these vaccines are highly effective, and that's one of the reasons we are recommending them for people across the country, he said.