Q: How long does it take to receive a response to a letter to the editor submitted to NEJM?

There’s both a good thing and a bad thing about letters to the editor, from a timeline perspective. As they are not scientific papers, they don’t go through the extensive review cycles that the former go through. But for the same reason, Associate Editors (AEs) turn their attention to these much later. The review cycle (done largely internally, unless the topic is too technical) takes about a week or so. Now, it could be more in case you reviewed/critiqued another paper – this is because the letter would most probably be accompanied by a response to your letter. Based on this, you can do the math. :-)

For more information on letters to the editor, you may refer to these previous queries:

• Should I withdraw my manuscript if the journal editor recommends it to be submitted as Letter to Editor?
• Should letters to the editor be checked for factual accuracy before publication?
• Is it ethical to publish a reply to a "Letter to the Editor" without publishing the original letter?

Hope that helps. And hope you hear from them soon.