Scientists created safe and effective vaccines against Covid-19 at an unprecedented speed. But, according to industry leaders, the next generation of Covid shots will be low in cost, easier to deliver and preserve and effective against more viruses, media reports said on Tuesday.

The pharma companies aim to develop shots that will be more effective against certain variants of the SARS-CoV-2 virus, that causes Covid-19, or even cover all viruses in the larger coronavirus family, the USA Today reported.

The new vaccines, currently being tested, will be of a single dose, do not require to be kept cold, have fewer side effects, can be produced more efficiently, and can be delivered without needles. This will enable it to be provided in rural areas and the developing world.

"There's a long history within vaccinology of second-generation vaccines being multiply improved over first-generation vaccines. That's just the way things go," Scot Roberts, chief scientific officer of Altimmune, a biotech company based in Gaithersburg, Maryland, that is developing an inhaled vaccine, was quoted as saying.

None of these second-generation Covid-19 vaccines will be ready until at least this summer, and many, including Altimmune's, not until early next year at the earliest. Further, no single vaccine will have all the desired attributes, experts said.

Most companies investing in Covid-19 vaccines are banking on the idea that regular boosters will be necessary.

Novavax's studies in monkeys have shown that giving a booster dose a year after initial vaccination yields "spectacular results", the report said. The company is soon expected to start human trials.

Several companies, including Moderna and CureVac are testing whether people are better protected if they receive an additional dose of the same vaccine, or a shot tailored to one or more of the variants circulating, the report said.