With Covid-19 vaccination ramping up and all adults being able to get the jab from Friday, health experts have warned against complacency in following non-pharmaceutical interventions.

Experts warn that the slow decline in the number of new Covid-19 cases and deaths could mean the country might experience the fourth wave as soon as the third wave ends.

Gauteng has reached the peak of the third wave, while KwaZulu-Natal and the Western Cape are still experiencing high case numbers.

On Thursday, the country recorded 13 671 new cases with a positivity rate of 19.9%. There were also 317 reported deaths.

Dr Aslam Dasoo from the Progressive Health Forum says "the long tail" of the third wave dominated by the Delta variant was worrying.

"Portugal had a wave two and three, weeks after they had determined that the previous wave had ended. We have to be careful about this. This long tail of the third wave may be giving us a very short interval before a fourth wave starts. The most important thing about the fourth wave will be the level of vaccination. The strength of the fourth wave is more dependent on that than anything else."

Dr Benjamin Kagina, a senior researcher and vaccinologist at Vaccines for Africa, agreed that the current wave trajectory was worrying.

"The current report that we are seeing is that the deaths are still high, and the positivity rate is also very high.  It's not a signal that we are out of the woods yet."

He says despite being fatigued, people needed to guard against being complacent.

"Every time people hear that the third wave is coming to an end, people relax. People have been quite jaded by this mask-wearing, social distancing. Every time there is good news, people relax a bit. Despite us feeling tired, the current variant that is causing the pandemic to be this bad is highly transmissible, so we must continue being safe even after vaccination."

On Thursday, Cabinet announced that vaccinations would be open to all adults from Friday.

The system was supposed to open on 1 September for the 18-plus cohort, but the date had been brought forward by two weeks. So far, about seven-million people had been partially vaccinated and about four-million fully vaccinated.

Crisp said they hoped young people would boost the ailing vaccination drive. Vaccination numbers had decreased in the past three weeks.

"They will boost the vaccination drive for a while. The 35-plus group did that for a while and then lost interest which was disappointing, really."

Kagina said allowing all willing adults to vaccinate should have been done earlier.

"We have been operating in a situation where the supply has been way less than the demand and using the risk-based approach to prioritise who needed to be vaccinated is ethical and sensible. However, we are now seeing a slight shift in supply being more than demand. Therefore, we need to give anybody who demands vaccination as quickly as possible so that we are left with the group that is unsure and have a much more targeted approach for them."

While being vaccinated is critical, he warned that people still needed to follow non-pharmaceutical interventions like wearing masks and social distancing.

"Vaccination is to add to what we are already doing. Especially because we have vaccinated a few people. Vaccination doesn't mean you can never get the virus. It means in the unlikely event you get infected, you will get a mild disease and not die."