The British and Irish rugby team will play the first game of their six-week tour of South Africa on Saturday, despite an escalating coronavirus outbreak in the host country that forced the entire Springboks squad to self-isolate.

The quadrennial tour by the Lions, made up of the best players from England, Ireland, Scotland and Wales, is the most anticipated clash in this year’s rugby calendar and among the most lucrative events in the sport’s schedule.

Although concerns over playing top-level sport in a pandemic put the tour in doubt, organisers decided to press ahead with the three international games and five warm-up matches.

The tour provides income not only to the four rugby unions that share ownership of the Lions but also the host country. This cash injection is particularly needed after 18 months of financial struggles and pandemic-induced disruption.

The last Lions tour, to New Zealand in 2017, was worth NZ$245m to that country’s gross domestic product, according to New Zealand Rugby, which made a NZ$33.4m profit that year.

“They’ll do anything they possibly can to make it happen,” said Steve Martin, global chief executive of the M&C Saatchi Sport & Entertainment agency. “The Lions tour, because it’s only once every four years, they’ve got to capitalise on it.”

Yet in a sign of the anxiety surrounding the tour, the games will be played in empty stadiums. This means no paying home supporters and none of the thousands of British and Irish fans who normally travel to watch a Lions series, and who provide a huge boost to the host nation’s economy. More than 342,000 seats were filled in 2017 and almost 26,000 visitors travelled to New Zealand to watch.

Mark Alexander, president of the South African Rugby Union, the domestic governing body, told local media this week that the Lions tour would go ahead but that it “would be ridiculous to host spectators when we’re in the crisis”.

Yet all South African club and amateur rugby games are suspended amid a devastating third wave focused on the country’s economic hub, Gauteng.

Recorded daily new cases in South Africa have hit 13,000 in recent days and hospitals are filling up, with the wave believed by epidemiologists to be driven by the Delta variant.

On the day the Lions arrived this week, South Africa entered its second most severe level of lockdown that included night-time curfews and a ban on alcohol sales.

Brian Moore, the broadcaster and former England forward who played for the Lions in 1989 and 1993, said the authorities had been forced to make a tough decision.

“It was either some version of this or nothing,” he told the Financial Times. “Especially given the statements from South Africa about their financial situation, it almost had to go ahead.”

Springbok players during the South Africa national men’s rugby team captains run in Johannesburg

The Lions believe that testing, social distancing, mask-wearing, sanitisation and the absence of fans would help protect their “bio-secure bubble”. “The South African government and our own medical advisory group are happy for the tour to continue,” the Lions said.

Rescheduling the matches would have been a costly and challenging task because of the sport’s congested calendar. Organisers also resisted switching to the UK, where fans have this week been able to watch the Euro 2020 football tournament and the Wimbledon tennis championships.

Moore said this would have been the best solution: “The safety of everyone involved has to be a concern [and] that unfortunately is not a given.”

But he added that “if they can pull off a compelling and competitive series it will show the strength of the Lions brand.”

Preparations of the home side, whose last competitive match was the 2019 World Cup final win over England, have also been disrupted. The Springboks were forced to cancel training and put their squad into self isolation last weekend after three players tested positive for the virus, although practice has since resumed.

Even with the Lions tour going ahead, Jurie Roux, SARU chief executive, has warned that rugby in the sport-loving country was walking a “financial tightrope”.

It cut costs after the pandemic struck, which limited net losses to 7.9m rand in 2020 even though broadcast and sponsorship revenue fell to 669m rand compared with the forecast 1.3bn rand.

It expects revenues to recover to 1bn rand this year, although this remains short of pre-pandemic levels.