Pascal Wehrlein will be back in action with Sauber this weekend, having missed the first two races of the season because of a back injury he suffered in an accident in the Race of Champions in Miami in January. There has been some speculation that the move was political, but this is not the case at all.
Wehrlein did not break any vertebrae, despite what has been said. He suffered a number of hairline fractures in a number of thoracic vertebrae (in effect, cracks) in the middle segment of the spine, below the cervical vertebrae of the neck and above those in the lumbar area at the bottom of the spine. The primary problem has not been the fractures, but rather the intervertebral discs, which are the spongy pads that are situated between each vertebra and act as shock absorbers for the human body. When these are compressed they take time to recover, particularly in the thoracic section because they are thinner than the other discs.
This means that training is a problem because one wants to avoid both further compression (not to mention pain) and so Wehrlein has been making a sensible but necessarily slow recovery. He tried to get back into action in Australia but realised that he was not sufficiently fit to compete and so withdrew, and so was replaced by Antonio Giovinazzi.
Now, it seems that he is confident that he can go the distance.