Ottawa, Apr 13 (IANS): As the Chief Public Health Officer of Canada, Theresa Tam, has confirmed that the country is expericing its sixth wave of Covid-19, the National Advisory Council on Immunization (NACI) has strengthened its guidance on boosters dose against the virus.

NACI said in a statement on Tuesday that those aged 18 or above are now "strongly recommended" to receive a first booster dose, Xinhua news agency reported.

Adolescents between 12 and 17 years of age "should" be offered a first booster dose if they have an underlying medical condition that puts them at high risk of severe outcomes from Covid, NACI said.

In addition, NACI recommended that a first booster dose be offered to anyone aged 12 years or above in the context of heightened epidemiological risk.

It said that booster doses should be given at least six months after the primary series of Covid vaccines, noting that the guidance change is based on considering additional data on the duration of protection from a primary Covid vaccine series, the safety and effectiveness of a first booster dose in adolescents and adults, and the changing epidemiology of Covid in Canada.

Tam said the latest rise in cases across the country is fuelled by the BA.2 subvariant of Omicron. "We can say we are experiencing a sixth wave in Canada, generally speaking."

According to a statement from the Chief Public Health Officer, recent seven-day averages showed an ongoing marked increase in average daily case counts, as well as rising trends in severe illness in most jurisdictions.

Likewise, laboratory test positivity during the latest seven-day period ending April 10 increased to 19 per cent nationally, and community wastewater data continued to signal sharply rising trends in the number of localities across the country, the statement said.